Effect of training and detraining on the expression of heat shock proteins in m. triceps brachii of untrained males and females

Unveiling the role of exercise in modulating plasma heat shock protein 27 levels: insights for exercise immunology and cardiovascular health

Cardiovascular disease is one of the leading causes of mortality worldwide, primarily driven by atherosclerosis, a chronic inflammatory condition contributing significantly to fatalities. Various biological determinants affecting cardiovascular health across different age and sex groups have been identified. In this context, recent attention has focused on the potential therapeutic and preventive role of increasing circulating levels of heat shock protein 27 (plasma HSP27) in combating atherosclerosis. Plasma HSP27 is recognized for its protective function in inflammatory atherogenesis, offering promising avenues for intervention and management strategies against this prevalent cardiovascular ailment. Exercise has emerged as a pivotal strategy in preventing and managing cardiovascular disease, with literature indicating an increase in plasma HSP27 levels post-exercise. However, there is limited understanding of the impact of exercise on the release of HSP27 into circulation. Clarifying these aspects is crucial for understanding the role of exercise in modulating plasma HSP27 levels and its potential implications for cardiovascular health across diverse populations. Therefore, this review aims to establish a more comprehensive understanding of the relationship between plasma HSP27 and exercise.

Transcriptome analysis of skeletal muscle in dermatomyositis, polymyositis, and dysferlinopathy, using a bioinformatics approach

Background

Polymyositis (PM) and dermatomyositis (DM) are two distinct subgroups of idiopathic inflammatory myopathies. Dysferlinopathy, caused by a dysferlin gene mutation, usually presents in late adolescence with muscle weakness, degenerative muscle changes are often accompanied by inflammatory infiltrates, often resulting in a misdiagnosis as polymyositis.

Objective

To identify differential biological pathways and hub genes related to polymyositis, dermatomyositis and dysferlinopathy using bioinformatics analysis for understanding the pathomechanisms and providing guidance for therapy development.

Methods

We analyzed intramuscular ribonucleic acid (RNA) sequencing data from seven dermatomyositis, eight polymyositis, eight dysferlinopathy and five control subjects. Differentially expressed genes (DEGs) were identified by using DESeq2. Enrichment analyses were performed to understand the functions and enriched pathways of DEGs. A protein-protein interaction (PPI) network was constructed, and clarified the gene cluster using the molecular complex detection tool (MCODE) analysis to identify hub genes.

Results

A total of 1,048, 179 and 3,807 DEGs were detected in DM, PM and dysferlinopathy, respectively. Enrichment analyses revealed that upregulated DEGs were involved in type 1 interferon (IFN1) signaling pathway in DM, antigen processing and presentation of peptide antigen in PM, and cellular response to stimuli in dysferlinopathy. The PPI network and MCODE cluster identified 23 genes related to type 1 interferon signaling pathway in DM, 4 genes (PDIA3, HLA-C, B2M, and TAP1) related to MHC class 1 formation and quality control in PM, and 7 genes (HSPA9, RPTOR, MTOR, LAMTOR1, LAMTOR5, ATP6V0D1, and ATP6V0B) related to cellular response to stress in dysferliniopathy.

Conclusion

Overexpression of genes related to the IFN1 signaling pathway and major histocompatibility complex (MHC) class I formation was identified in DM and PM, respectively. In dysferlinopathy, overexpression of HSPA9 and the mTORC1 signaling pathway genes was detected.

Heat shock proteins in adaptation to physical activity

The review article presents the author’s model of one of the blocks of the integrated adaptation mechanism to physical activity and the accompanying moderate heat effects. The participation of heat shock proteins in the stabilization of the tertiary structure and in the restoration of the function of proteins damaged by temperature and physical stressors but performing catalytic, transport, reception or protective role and being involved in the processes of contraction- relaxation and muscle and bone tissue remodeling is discussed.

Moderate-Intensity Exercise Training in Association with Insulin Promotes Heat Shock Proteins 70 and 90 Expressions in Testicular Tissue of Experimental Type 1 Diabetes

Objective

The current research was designed to analyze the effect of moderate-intensity exercise training (MEXT), solely and simultaneous with insulin, on the network between oxidative stress and Hsp70 and Hsp90 chaperones after experimental type I diabetes (DM) induction in rats.

Materials and Methods

In the experimental study, 36 mature Wistar rats were assigned into control and experimental type I DM-induced groups, and then the diabetic animals were categorized to sedentary type I DM-induced (SDM), exercise training-sole without DM (E), exercise training DM-induced (EDM), insulin-treated sedentary DM-induced (ISDM), and exercise training insulin-treated DM-induced (EIDM) groups. After 6 weeks, Johnson’s score was evaluated to analyze the spermatogenesis ratio.

Results

The Hsp70 and Hsp90 expression levels, testicular total antioxidant capacity (TAC), protein peroxidation ratio, testicular DNA fragmentation ratio, and mRNA damage were investigated. The animals in EDM and EIDM groups (solely and simultaneously) represented a significant (P<0.05) improvement in Johnson’s score, spermatogenesis, and TAC ratios versus SDM animals. Moreover, the DM-induced DNA and mRNA damage and protein peroxidation ratio were significantly (P<0.05) recovered in EDM and ISDM groups, which was more remarkable in the EIDM group. The EDM and EIDM groups exhibited significant (P<0.05) increment in Hsp70 and Hsp90 expression levels versus the control and SEDT1 animals. However, the EIDM group exhibited no significant changes compared to the control animals.

Conclusion

The EX could ameliorate the EDT1-induced detrimental impact by up-regulating Hsp70 and Hsp90 expressions. Meanwhile, it exerts potentially more effective impact, when it is considered simultaneously with insulin therapy.

An Overview of Physical Exercise and Antioxidant Supplementation Influences on Skeletal Muscle Oxidative Stress

One of the essential injuries caused by moderate to high-intensity and short-duration physical activities is the overproduction of reactive oxygen species (ROS), damaging various body tissues such as skeletal muscle (SM). However, ROS is easily controlled by antioxidant defense systems during low to moderate intensity and long-term exercises. In stressful situations, antioxidant supplements are recommended to prevent ROS damage. We examined the response of SM to ROS generation during exercise using an antioxidant supplement treatment strategy in this study. The findings of this review research are paradoxical due to variances in antioxidant supplements dose and duration, intensity, length, frequency, types of exercise activities, and, in general, the lack of a regular exercise and nutrition strategy. As such, further research in this area is still being felt.

Muscular HSP70 content is higher in elderly compared to young, but is normalized after 12 weeks of strength training

Purpose

Aging is associated with increased myocellular stress and loss of muscle mass and function. Heat shock proteins (HSPs) are upregulated during periods of stress as part of the cells protective system. Exercise can affect both acute HSP regulation and when repeated regularly counteract unhealthy age-related changes in the muscle. Few studies have investigated effects of exercise on HSP content in elderly. The aim of the study was to compare muscular HSP levels in young and elderly and to investigate how training affects HSP content in muscles from aged males and females.

Methods

Thirty-eight elderly were randomized to 12 weeks of strength training (STG), functional strength training (FTG) or a control group (C). To compare elderly to young, 13 untrained young performed 11 weeks of strength training (Y). Muscle biopsies were collected before and after the intervention and analyzed for HSP27, αB-crystallin and HSP70.

Results

Baseline HSP70 were 35% higher in elderly than in young, whereas there were no differences between young and elderly in HSP27 or αB-crystallin. After the training intervention, HSP70 were reduced in STG (− 33 ± 32%; P = 0.001) and FTG (− 28 ± 30%; P = 0.012). The decrease in HSP70 was more pronounced in the oldest. In contrast, Y increased HSP27 (134 ± 1%; P < 0.001) and αB-crystallin (84 ± 94%; P = 0.008).

Conclusion

Twelve weeks of STG or FTG decreased the initial high levels of HSP70 in aged muscles. Thus, regular strength training can normalize some of the increases in cellular stress associated with normal aging, and lead to a healthier cellular environment in aged muscle cells.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00421-021-04633-4.

Effects of Resistance Training on the Redox Status of Skeletal Muscle in Older Adults

The aim of this study was to investigate the effects of resistance training (RT) on the redox status of skeletal muscle in older adults. Thirteen males aged 64 ± 9 years performed full-body RT 2x/week for 6 weeks. Muscle biopsies were obtained from the vastus lateralis prior to and following RT. The mRNA, protein, and enzymatic activity levels of various endogenous antioxidants were determined. In addition, skeletal muscle 4-hydroxynonenal and protein carbonyls were determined as markers of oxidative damage. Protein levels of heat shock proteins (HSPs) were also quantified. RT increased mRNA levels of all assayed antioxidant genes, albeit protein levels either did not change or decreased. RT increased total antioxidant capacity, catalase, and glutathione reductase activities, and decreased glutathione peroxidase activity. Lipid peroxidation also decreased and HSP60 protein increased following RT. In summary, 6 weeks of RT decreased oxidative damage and increased antioxidant enzyme activities. Our results suggest the older adult responses to RT involve multi-level (transcriptional, post-transcriptional, and post-translational) control of the redox status of skeletal muscle.

Role of heat shock proteins 70/90 in exercise physiology and exercise immunology and their diagnostic potential in sports

Heat shock proteins (HSPs) are molecular chaperones facilitating the unfolding or folding of secondary structures of proteins, their client proteins, in cellular stress situations. Various internal and external physiological and mechanical stress factors induce a homeostatic imbalance, followed by an increased expression of HSP70 and HSP90. Exercise is a stress factor, too, and its cumulative physiological perturbation manifests at a cellular level by threatening the protein homeostasis of various cell types. Consequently, an increase of HSP70/90 was described in plasma and mononuclear cells and various organs and tissues, such as muscle, liver, cardiac tissue, and brain, after an acute bout of exercise. The specific response of HSP70/90 seems to be strongly related to the modality of exercise, with several dependent factors such as duration, intensity, exercise type, subjects’ training status, and environmental factors, e.g., temperature. It is suggested that HSP70/90 play a major role in immune regulation and cell protection during exercise and in the efficiency of regeneration and reparation processes. During long-term training, HSP70/90 are involved in preconditioning and adaptation processes that might also be important for disease prevention and therapy. With regard to their highly sensitive and individual response to specific exercise and training modalities, this review discusses whether and how HSP70 and HSP90 can be applied as biomarkers for monitoring exercise and training.

Skeletal muscle cold shock and heat shock protein mRNA response to aerobic exercise in different environmental temperatures

The response of cold shock proteins to exercise and environmental temperature in human skeletal muscle is not known. The purpose of this study was to determine the early mRNA response of human stress proteins to endurance exercise and environmental temperatures. Seven recreationally trained males cycled for 1 hour at 60% VO_2peak in 7°C, 20°C, and 33°C with biopsies taken pre- and 3 hours post-exercise. Gene expression for heat shock and cold shock proteins were analyzed using qRT-PCR on muscle biopsy samples from the vastus lateralis. RBM3 mRNA was reduced 1.43 ± 0.10 fold (p = 0.006) while there was a trend for CIRP to decrease1.27 ± 0.14 fold (p = 0.059) from pre- to 3 h post-exercise. CIRP and RBM3 mRNA were not different between temperatures (p = 0.273 and p = 0.686, respectively). HSP70 mRNA was 2.27 ± 0.23 fold higher 3 h post-exercise when compared to pre-exercise (p = 0.002) but was not significantly different between temperatures (p = 0.103). HSP27, HSP90, and HSF1 mRNA did not change from pre- to post-exercise (p = 0.052, p = 0.324, p = 0.795) and were not different between temperatures (p = 0.247, p = 0.134, p = 0.808). These data indicate that exposure to mild heat and cold during aerobic exercise have limited effect on the skeletal muscle mRNA expression of heat shock and cold shock proteins. However, skeletal muscle mRNA of cold shock proteins decrease, while HSP70 mRNA increases in response to a low to moderate intensity aerobic exercise bout.

Lifelong Football Training: Effects on Autophagy and Healthy Longevity Promotion

Aging is a physiological process characterized by a progressive decline of biological functions and an increase in destructive processes in cells and organs. Physical activity and exercise positively affects the expression of skeletal muscle markers involved in longevity pathways. Recently, a new mechanism, autophagy, was introduced to the adaptations induced by acute and chronic exercise as responsible of positive metabolic modification and health-longevity promotion. However, the molecular mechanisms regulating autophagy in response to physical activity and exercise are sparsely described. We investigated the long-term adaptations resulting from lifelong recreational football training on the expression of skeletal muscle markers involved in autophagy signaling. We demonstrated that lifelong football training increased the expression of messengers: RAD23A, HSPB6, RAB1B, TRAP1, SIRT2, and HSBPB1, involved in the auto-lysosomal and proteasome-mediated protein degradation machinery; of RPL1, RPL4, RPL36, MRLP37, involved in cellular growth and differentiation processes; of the Bcl-2, HSP70, HSP90, PSMD13, and of the ATG5-ATG12 protein complex, involved in proteasome promotion and autophagy processes in muscle samples from lifelong trained subjects compared to age-matched untrained controls. In conclusion, our results indicated that lifelong football training positively influence exercise-induced autophagy processes and protein quality control in skeletal muscle, thus promoting healthy aging.

Exercise, heat shock proteins and insulin resistance

Best known as chaperones, heat shock proteins (HSPs) also have roles in cell signalling and regulation of metabolism. Rodent studies demonstrate that heat treatment, transgenic overexpression and pharmacological induction of HSP72 prevent high-fat diet-induced glucose intolerance and skeletal muscle insulin resistance. Overexpression of skeletal muscle HSP72 in mice has been shown to increase endurance running capacity nearly twofold and increase mitochondrial content by 50%. A positive correlation between HSP72 mRNA expression and mitochondrial enzyme activity has been observed in human skeletal muscle, and HSP72 expression is markedly decreased in skeletal muscle of insulin resistant and type 2 diabetic patients. In addition, decreased levels of HSP72 correlate with insulin resistance and non-alcoholic fatty liver disease progression in livers from obese patients. These data suggest the targeted induction of HSPs could be a therapeutic approach for preventing metabolic disease by maintaining the body's natural stress response. Exercise elicits a number of metabolic adaptations and is a powerful tool in the prevention and treatment of insulin resistance. Exercise training is also a stimulus for increased HSP expression. Although the underlying mechanism(s) for exercise-induced HSP expression are currently unknown, the HSP response may be critical for the beneficial metabolic effects of exercise. Exercise-induced extracellular HSP release may also contribute to metabolic homeostasis by actively restoring HSP72 content in insulin resistant tissues containing low endogenous levels of HSPs.This article is part of the theme issue 'Heat shock proteins as modulators and therapeutic targets of chronic disease: an integrated perspective'.

Vitamin C and E supplementation does not affect heat shock proteins or endogenous antioxidants in trained skeletal muscles during 12 weeks of strength training

Background

Supplementation with large doses of antioxidants, such as vitamin C and E, has been shown to blunt some adaptations to endurance training. The effects of antioxidant supplementation on adaptations to strength training is sparsely studied. Herein we investigated the effects of vitamin C and E supplementation on acute stress responses to exercise and adaptation to traditional heavy load strength training.

Methods

In a double blind placebo-controlled design, twenty-eight, young, trained males and females were randomly assigned to receive either vitamin C and E (C: 1000 mg, E: 235 mg, per day) or placebo supplements, and underwent strength training for 10 weeks. After five weeks, a subgroup conducted a strength training session to investigate acute stress responses. Muscle samples were obtained to investigate changes in stress responses and in proteins and mRNA related to the heat shock proteins (HSPs) or antioxidant enzymes.

Results

The acute responses to the exercise session revealed activation of the NFκB pathway indicated by degradation of IκBα in both groups. Vitamin C and E supplementation had, however, no effects on the acute stress responses. Furthermore, ten weeks of strength training did not change muscle αB-crystallin, HSP27, HSP70, GPx1 or mnSOD levels, with no influence of supplementation.

Conclusions

Our results showed that although vitamin C and E supplementation has been shown to interfere with training adaptations, it did not affect acute stress responses or long-term training adaptations in the HSPs or antioxidant enzymes in this study.

Electronic supplementary material

The online version of this article (doi:10.1186/s40795-017-0185-8) contains supplementary material, which is available to authorized users.

Short-term treadmill exercise in a cold environment does not induce adrenal Hsp72 and Hsp25 expression

Heat shock proteins (Hsps) have a critical role in maintaining cellular homeostasis and in protecting cells from a range of acute and chronic stressful conditions. Treadmill running exercise results in increased Hsp72 and Hsp25 levels in various tissues and heat production during exercise has been shown to be the main factor for the increased levels of Hsp72 in myocardium. Since the adrenal gland plays a vital role in general response to stress, regulation of Hsps in adrenal glands following stressful events seems to be critical for controlling the whole-body stress response appropriately. This study tested the hypothesis of whether elevation of temperature is solely responsible for exercise-induced adrenal Hsp72 and Hsp25 expression. Female Sprague-Dawley rats (3 months old) were randomly assigned to either a sedentary control group or one of two treadmill-running groups: a cold exercise group run in a cold room at 4 °C (CE), and a warm exercise group run at 25 °C temperature (WE). Animals were run 60 min a day at 30 m min-1 speed for 4 consecutive days following adaptation to treadmill exercise. Exercise resulted in a significant elevation of body temperature only in the WE group (p < 0.05). Adrenal Hsp72 and Hsp25 levels were significantly higher in the WE group compare to the other groups (p < 0.05). These data demonstrated that exercise-related elevations of body temperature could be the only factor for the inductions of adrenal Hsp72 and Hsp25 expression.

Strength Training with Vascular Occlusion: A Review of Possible Adaptive Mechanisms

Strength training with blood flow restriction, or KAATSU training, has been shown to be as effective as conventional strength training to promote muscular strength and hypertrophy. Several mechanisms have been suggested as hypotheses to explain the adaptations arising from this training method. Among these is metabolic stress, which exerts important physiological effects and may influence the training adaptations in question. In addition, hypoxia produced by the technique may change the neural recruitment pattern. Growth hormone (GH) concentrations increase as a result of practicing this method, which can trigger an increase in plasmatic and, perhaps, muscular insulin-like growth factor-1 (IGF-1) concentrations. The increase in concentrations of these factors can play a leading role in responses to KAATSU training. Among the effects of the GH/IGF-1 axis in muscle cells is the increase in the signalling pathway activity of the mammalian target of rapamycin (mTOR), which has been associated with increased protein synthesis. On the other hand, the decrease in the activity of the myostatin pathway, which has an antagonistic effect to mTOR, has been demonstrated after training with occlusion. Other factors, such as increases in the expression of heat shock proteins, may play an important role in adaptations to exercise. Nitric oxide synthase could increase nitric oxide concentration, which in turn has an effect on satellite cells and blood flow. However, despite the results obtained, the transfer to other situations (e.g. speed sports) is not yet clear.

The effect of strength training on muscle cellular stress in prostate cancer patients on ADT

BACKGROUND

Androgen deprivation therapy (ADT) for prostate cancer (PCa) is associated with several side effects, including loss of muscle mass. Muscle atrophy is associated with reduced mitochondrial function and increased muscle cellular stress that may be counteracted by strength training. Thus, the aim of this study was to investigate the effect of strength training on mitochondrial proteins and indicators of muscle cellular stress in PCa patients on ADT.

METHODS

Men diagnosed with locally advanced PCa receiving ADT were randomised to a strength training group (STG) (n=16) or a control group (CG) (n=15) for 16 weeks. Muscle biopsies were collected pre- and post-intervention from the vastus lateralis muscle, and analysed for mitochondrial proteins (citrate synthase, cytochrome c oxidase subunit IV (COXIV), HSP60) and indicators of muscle cellular stress (heat shock protein (HSP) 70, alpha B-crystallin, HSP27, free ubiquitin, and total ubiquitinated proteins) using Western blot and ELISA.

RESULTS

No significant intervention effects were observed in any of the mitochondrial proteins or indicators of muscle cellular stress. However, within-group analysis revealed that the level of HSP70 was reduced in the STG and a tendency towards a reduction in citrate synthase levels was observed in the CG. Levels of total ubiquitinated proteins were unchanged in both groups.

CONCLUSION

Although reduced HSP70 levels indicated reduced muscle cellular stress in the STG, the lack of an intervention effect precluded any clear conclusions.

Heat shock response and autophagy--cooperation and control

Protein quality control (proteostasis) depends on constant protein degradation and resynthesis, and is essential for proper homeostasis in systems from single cells to whole organisms. Cells possess several mechanisms and processes to maintain proteostasis. At one end of the spectrum, the heat shock proteins modulate protein folding and repair. At the other end, the proteasome and autophagy as well as other lysosome-dependent systems, function in the degradation of dysfunctional proteins. In this review, we examine how these systems interact to maintain proteostasis. Both the direct cellular data on heat shock control over autophagy and the time course of exercise-associated changes in humans support the model that heat shock response and autophagy are tightly linked. Studying the links between exercise stress and molecular control of proteostasis provides evidence that the heat shock response and autophagy coordinate and undergo sequential activation and downregulation, and that this is essential for proper proteostasis in eukaryotic systems.

Heat shock proteins and exercise adaptations. Our knowledge thus far and the road still ahead

By its very nature, exercise exerts a challenge to the body's cellular homeostatic mechanisms. This homeostatic challenge affects not only the contracting skeletal muscle but also a number of other organs and results over time in exercise-induced adaptations. Thus it is no surprise that heat shock proteins (HSPs), a group of ancient and highly conserved cytoprotective proteins critical in the maintenance of protein and cellular homeostasis, have been implicated in exercise/activity-induced adaptations. It has become evident that HSPs such as HSP72 are induced or activated with acute exercise or after chronic exercise training regimens. These observations have given scientists an insight into the protective mechanisms of these proteins and provided an opportunity to exploit their protective role to improve health and physical performance. Although our knowledge in this area of physiology has improved dramatically, many questions still remain unanswered. Further understanding of the role of HSPs in exercise physiology may prove beneficial for therapeutic targeting in diseased patient cohorts, exercise prescription for disease prevention, and training strategies for elite athletes.

Short-Wave Diathermy Pretreatment and Inflammatory Myokine Response After High-Intensity Eccentric Exercise

CONTEXT

Various modalities have been used to pretreat skeletal muscle to attenuate inflammation.

OBJECTIVE

To determine the effects of short-wave diathermy (SWD) preheating treatment on inflammation and stress markers after eccentric exercise.

DESIGN

Controlled laboratory study.

SETTING

University laboratory setting.

PATIENTS OR OTHER PARTICIPANTS

Fifteen male (age = 22 ± 4.9 years, height = 179.75 ± 9.56 cm, mass = 82.22 ± 12.67 kg) college-aged students.

INTERVENTION(S)

Seven participants were selected randomly to receive 40 minutes of SWD heat treatment (HT), and 8 participants served as the control (CON) group and rested without SWD. Both groups completed 7 sets of 10 repetitions of a high-intensity eccentric exercise protocol (EEP) at 120% of the 1-repetition maximum (1-RM) leg extension.

MAIN OUTCOME MEASURE(S)

We biopsied muscles on days 1, 3 (24 hours post-EEP), and 4 (48 hours post-EEP) and collected blood samples on days 1, 2 (4 hours post-EEP), 3, and 4. We determined 1-RM on day 2 (24 hours post-SWD) and measured 1-RM on days 3 and 4. We analyzed the muscle samples for interleukin 6 (IL-6), tumor necrosis factor α, and heat shock protein 70 and the blood for serum creatine kinase.

RESULTS

We found a group × time interaction for intramuscular IL-6 levels after SWD (F2,26 = 7.13, P = .003). The IL-6 decreased in HT (F1,6 = 17.8, P = .006), whereas CON showed no change (P > .05). We found a group × time interaction for tumor necrosis factor α levels (F2,26 = 3.71, P = .04), which increased in CON (F2,14 = 7.16, P = .007), but saw no changes for HT (P > .05). No group × time interactions were noted for 1-RM, heat shock protein 70, or creatine kinase (P > .05).

CONCLUSIONS

The SWD preheating treatment provided a treatment effect for intramuscular inflammatory myokines induced through high-intensity eccentric exercise but did not affect other factors associated with intense exercise and inflammation.

Two weeks of one-leg immobilization decreases skeletal muscle respiratory capacity equally in young and elderly men

Physical inactivity affects human skeletal muscle mitochondrial oxidative capacity but the influence of aging combined with physical inactivity is not known. This study investigates the effect of two weeks of immobilization followed by six weeks of supervised cycle training on muscle oxidative capacity in 17 young (23±1years) and 15 elderly (68±1years) healthy men. We applied high-resolution respirometry in permeabilized fibers from muscle biopsies at inclusion after immobilization and training. Furthermore, protein content of mitochondrial complexes I-V, mitochondrial heat shock protein 70 (mtHSP70) and voltage dependent anion channel (VDAC) were measured in skeletal muscle by Western blotting. The elderly men had lower content of complexes I-V and mtHSP70 but similar respiratory capacity and content of VDAC compared to the young. In both groups the respiratory capacity and protein content of VDAC, mtHSP70 and complexes I, II, IV and V decreased with immobilization and increased with retraining. Moreover, there was no overall difference in the response between the groups. When the intrinsic mitochondrial capacity was evaluated by normalizing respiration to citrate synthase activity, the respiratory differences with immobilization and training disappeared. In conclusion, aging is not associated with a decrease in muscle respiratory capacity in spite of lower complexes I-V and mtHSP70 protein content. Furthermore, immobilization decreased and aerobic training increased the respiratory capacity and protein contents of complexes I-V, mtHSP70 and VDAC similarly in the two groups. This suggests that inactivity and training alter mitochondrial biogenesis equally in young and elderly men.

Acute response and subcellular movement of HSP27, αB-crystallin and HSP70 in human skeletal muscle after blood-flow-restricted low-load resistance exercise

AIM

Heat-shock proteins (HSP) are important chaperones for stressed and damaged proteins. Low-load blood-flow-restricted resistance exercise (BFRE) is generally believed not to induce significant muscle damage, but is hitherto unverified with intracellular markers. Consequently, the aim of this study was to investigate the HSP response after BFRE in human skeletal muscle.

METHODS

Nine healthy volunteers performed five sets to failure of unilateral knee extension at 30% of 1RM with partial blood-flow restriction. The contralateral leg performed the same work with free blood flow. Muscle biopsies were collected before exercise, 1, 24 and 48 h after exercise and analysed for HSP27, αB-crystallin, HSP70, desmin, glycogen content and myosin heavy chain by immunohistochemistry, ELISA and western blotting.

RESULTS

One hour after exercise, HSP27 and αB-crystallin levels were reduced in the cytosolic and increased in the cytoskeletal fraction in the BFRE leg. HSP70 showed a delayed response and was increased over 48 h in the BFRE leg. Immunohistochemical analyses showed higher staining intensity of HSP70 in type 1 fibres in the BFRE leg at 24 and 48 h post-exercise. PAS staining showed decreased glycogen levels after BFRE, and interestingly, glycogen was still depleted 48 h after exercise in the same fibres displaying high HSP70 staining (type 1 fibres).

CONCLUSION

Translocation of HSP27 and αB-crystallin from cytosol to cytoskeletal structures indicates that cytoskeletal proteins are stressed during BFRE. However, overt signs of myofibrillar disruptions were not observed. Interestingly, the stress response was more pronounced in type 1 than in type 2 fibres and coincided with low glycogen levels.

Intramuscular heating through fluidotherapy and heat shock protein response

CONTEXT

Therapeutic modalities that can increase intramuscular temperature commonly are used to treat injuries in the clinical setting. Researchers recently have suggested that the physiologic changes occurring during an increase in temperature also could provide a cytoprotective effect for exercise-induced muscle damage.

OBJECTIVE(S)

To determine if the Fluidotherapy treatment increases the inducible expression of heat shock protein (HSP), to identify the rate of heating that occurs in the lower extremity with Fluidotherapy treatment, and to evaluate the relationship between the inducible expression of HSP and temperature.

DESIGN

Controlled laboratory study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

Six male (age = 21.67 ± 1.63 years, height = 180.09 ± 4.83 cm, mass = 87.60 ± 10.51 kg) and 6 female (age = 24.60 ± 4.59 years, height = 151.05 ± 35.76 cm, mass = 55.59 ± 14.58 kg) college-aged students.

INTERVENTION(S)

One lower extremity was randomly selected to receive the heat treatment, and the other extremity received no treatment.

MAIN OUTCOME MEASURE(S)

We measured intramuscular temperature every 10 minutes, determining peak intramuscular temperature by 2 identical sequential measurements, and we analyzed the time to peak temperature. We analyzed the amount of HSP70 expression and HSP27P:T (ratio of HSP27 to the total HSP27 expression) in the gastrocnemius and soleus muscles and measured baseline skinfold thickness and estradiol levels.

RESULTS

Fluidotherapy increased intramuscular temperature by 5.66 ± 0.78°C (t11 = 25.67, P < .001) compared with baseline temperature, with a peak temperature of 39.08°C ± 0.39°C occurring at 84.17 ± 6.69 minutes. We did not find a heat treatment effect for HSP70 or HSP27P:T in the gastrocnemius or soleus muscles (P > .05). Peak temperature and the percentage change of HSP70 were positively correlated for the gastrocnemius and soleus muscles (P < .05). We found no other correlations for skinfold thickness, sex, or estradiol levels (P > .05). No effect of sex for skinfold thickness or estradiol levels at baseline was discovered (P > .05).

CONCLUSIONS

This Fluidotherapy protocol increased the intramuscular temperature to a therapeutic level; however, it did not stimulate inducible HSP70 or HSP27P:T in the soleus and gastrocnemius muscles regardless of sex or skinfold thickness. These data confirmed that Fluidotherapy is an effective heating modality but suggested it is not an effective method for stimulating an HSP response in the lower limb.

Exercise training and work task induced metabolic and stress-related mRNA and protein responses in myalgic muscles

The aim was to assess mRNA and/or protein levels of heat shock proteins, cytokines, growth regulating, and metabolic proteins in myalgic muscle at rest and in response to work tasks and prolonged exercise training. A randomized controlled trial included 28 females with trapezius myalgia and 16 healthy controls. Those with myalgia performed ~7 hrs repetitive stressful work and were subsequently randomized to 10 weeks of specific strength training, general fitness training, or reference intervention. Muscles biopsies were taken from the trapezius muscle at baseline, after work and after 10 weeks intervention. The main findings are that the capacity of carbohydrate oxidation was reduced in myalgic compared with healthy muscle. Repetitive stressful work increased mRNA content for heat shock proteins and decreased levels of key regulators for growth and oxidative metabolism. In contrast, prolonged general fitness as well as specific strength training decreased mRNA content of heat shock protein while the capacity of carbohydrate oxidation was increased only after specific strength training.

Hypoxia-mediated prior induction of monocyte-expressed HSP72 and HSP32 provides protection to the disturbances to redox balance associated with human sub-maximal aerobic exercise

HSP72 is rapidly expressed in response to a variety of stressors in vitro and in vivo (including hypoxia). This project sought a hypoxic stimulus to elicit increases in HSP72 and HSP32 in attempts to confer protection to the sub-maximal aerobic exercise-induced disturbances to redox balance. Eight healthy recreationally active male subjects were exposed to five consecutive days of once-daily hypoxia (2,980 m, 75 min). Seven days prior to the hypoxic acclimation period, subjects performed 60 min of cycling on a cycle ergometer (exercise bout 1-EXB1), and this exercise bout was repeated 1 day post-cessation of the hypoxic period (exercise bout 2-EXB2). Blood samples were taken immediately pre- and post-exercise and 1, 4 and 8 h post-exercise for HSP72 and immediately pre, post and 1 h post-exercise for HSP32, TBARS and glutathione [reduced (GSH), oxidised (GSSG) and total (TGSH)], with additional blood samples obtained immediately pre-day 1 and post-day 5 of the hypoxic acclimation period for the same indices. Monocyte-expressed HSP32 and HSP72 were analysed by flow cytometry, with measures of oxidative stress accessed by commercially available kits. There were significant increases in HSP72 (P < 0.001), HSP32 (P = 0.03), GSSG (t = 9.5, P < 0.001) and TBARS (t = 5.6, P = 0.001) in response to the 5-day hypoxic intervention, whereas no significant changes were observed for GSH (P = 0.22) and TGSH (P = 0.25). Exercise-induced significant increases in HSP72 (P < 0.001) and HSP32 (P = 0.003) post-exercise in EXB1; this response was absent for HSP72 (P ≥ 0.79) and HSP32 (P ≥ 0.99) post-EXB2. The hypoxia-mediated increased bio-available HSP32 and HSP72 and favourable alterations in glutathione redox, prior to exercise commencing in EXB2 compared to EXB1, may acquiesce the disturbances to redox balance encountered during the second physiologically identical exercise bout.

Strength training elevates HSP27, HSP70 and αB-crystallin levels in musculi vastus lateralis and trapezius

A single bout of high-force exercise has been shown to increase the muscle levels of heat shock proteins (HSPs). Here, changes in the levels of HSPs after 2 and 11 weeks of strength training with either one or three sets per exercise were examined. Fifteen young men (27 ± 6 years, 182 ± 8 cm and 82 ± 13 kg) were randomized to train either one set in lower-body exercises and three sets in upper-body exercises (1L-3UB), or three sets in lower-body exercises and one set in upper-body exercises (3L-1UB). Biopsies from vastus lateralis and trapezius were obtained before, during (2 weeks) and after 11 weeks of strength training (3 bouts per week). The biopsies were analysed for HSP27 (cytosolic and cytoskeletal fractions) and HSP70 and αB-crystallin (cytosolic fraction). No evidence for an effect of training volume (1 vs. 3 sets) on the HSP response was found. For all subjects combined, HSP27 [186 ± 69% (mean ± SD)], HSP70 (146 ± 51%) and αB-crystallin (184 ± 82%) increased in the cytosolic fraction of vastus lateralis after 11 weeks of training. In the trapezius, the only observed increase was for HSP27 in the cytosolic fraction after 2 weeks of training (149 ± 59%). However, the trapezius contained somewhat higher levels of HSP70 and αB-crystallin than vastus lateralis at baseline. The HSP27 levels in the cytoskeletal compartment did not increase significantly in either muscle. In conclusion, strength training resulted-independent of training volume-in elevated levels of HSP27, HSP70 and αB-crystallin in the cytosolic compartment of the vastus lateralis. In the trapezius, only the cytosolic HSP27 levels were increased with training.

Early response of heat shock proteins to functional overload of the soleus and plantaris in rats and mice

Heat shock proteins (HSPs) are important factors in the response of skeletal muscles to chronic increases or decreases in activation and loading. The purpose of this study was to compare species-, time- and muscle-dependent changes in protein expression of Hsp20, Hsp25, αB-crystallin, Hsp72 and Hsp90 in response to functional overload (FO) in rats and mice. We compared protein levels of Hsp20, Hsp25, αB-crystallin, Hsp72 and Hsp90 in soleus and plantaris in baseline conditions and following 0.5, 1, 2, 3 and 7 days (rats) or 3 and 7 days (mice) of FO. Baseline levels of all HSPs were higher in rat soleus than plantaris, whereas only baseline expression of Hsp20 was higher in mouse soleus than plantaris. Levels of Hsp72 and Hsp90 were higher in plantaris and soleus of FO than control mice and rats after 3 and 7 days of FO. Protein levels and phosphorylation of Hsp25 in mouse plantaris and soleus were higher than control levels after 3 and 7 days of FO, except for soleus at 3 days. αB-crystallin levels were higher in plantaris of FO than control mice after 3 and 7 days of FO and in FO than control rats after 7 days of FO. Heat shock protein 20 was the least responsive, increasing only in 7 day FO rat plantaris compared with control rats. Overall, the results demonstrate that levels of both large and small HSPs increase with FO, suggesting a contributory role during the compensatory hypertrophy response.

Daily hypoxia increases basal monocyte HSP72 expression in healthy human subjects

Heat shock protein 72 (HSP72) performs vital roles within the body at rest and during periods of stress. In vitro, research demonstrates HSP72 induction in response to hypoxia. Recently, in vivo, an acute hypoxic exposure (75 min at 2,980 m) was sufficient to induce significant increases in monocyte expressed HSP72 (mHSP72) and a marker of oxidative stress in healthy human subjects. The purpose of the current study was to identify the impact of 10 consecutive days of hypoxic exposures (75 min at 2,980 m) on mHSP72 and erythropoietin (EPO) expression, markers of oxidative stress, and maximal oxygen consumption in graded incremental aerobic exercise. Eight male subjects were exposed to daily normobaric hypoxic exposures for 75 min at 2,980 m for 10 consecutive days, commencing and ceasing at 0930 and 1045, respectively. This stressor was sufficient to induce significant increases in mHSP72, which was significantly elevated from day 2 of the hypoxic exposures until 48 h post-final exposure. Notably, this increase had an initial rapid (30% day on day compared to baseline) and final slow phase (16% day on day compared to baseline) of expression. The authors postulate that 7-day hypoxic exposure in this manner would be sufficient to induce near maximum hypoxia-mediated basal mHSP72 expression. Elevated levels of mHSP72 are associated with acquired thermotolerance and provide cross tolerance to non-related stressors in vivo, the protocol used here may provide a useful tool for elevating mHSP72 in vivo. Aside from these major findings, significant transient daily elevations were seen in a marker of oxidative stress, alongside sustained increases in EPO expression. However, no physiologically significant changes were seen in maximal oxygen consumption or time to exhaustion.

Myofiber stress-response in myositis: parallel investigations on patients and experimental animal models of muscle regeneration and systemic inflammation

Introduction

The endoplasmic reticulum (ER) stress-response, evoked in mice by the overexpression of class I major histocompatibility complex antigen (MHC-I), was proposed as a major mechanism responsible for skeletal muscle damage and dysfunction in autoimmune myositis. The present study was undertaken to characterize in more detail the ER stress-response occurring in myofibers of patients with inflammatory myopathies, focusing on the expression and distribution of Grp94, calreticulin and Grp75, three ER chaperones involved in immunomodulation.

Methods

Muscle biopsies were obtained from seven healthy subjects and 29 myositis patients, who were subdivided into groups based on the morphological evidence of inflammation and/or sarcolemmal immunoreactivity for MHC-I. Biopsies were analyzed by means of immunohistochemistry and western blot using anti-Grp94, anti-calreticulin and anti-Grp75 specific antibodies. Parallel analyses on these ER chaperones were conducted in rabbit and/or murine skeletal muscle after experimental induction of regeneration or systemic inflammation.

Results

Upregulation of Grp94 characterized regenerating myofibers of myositis patients (P = 0.03, compared with values detected in biopsies without signs of muscle regeneration) and developing and regenerating myofibers of mouse muscles. Conversely, levels of calreticulin and Grp75 increased about fourfold and twofold, respectively, in patient biopsies positive for sarcolemmal MHC-I immunoreactivity, compared with healthy subjects and patients negative for both inflammation and MHC-I labeling (P < 0.005). Differently from calreticulin, the Grp75 level increased significantly also in patient biopsies that displayed occasional sarcolemmal MHC-I immunoreactivity (P = 0.002), suggesting the interference of other mechanisms. Experimental systemic inflammation achieved in mice and rabbits by a single injection of bacterial lipopolysaccharide significantly increased Grp75 and calreticulin but not MHC-I expression in muscles.

Conclusions

These results indicate that, in myositis patients, muscle regeneration and inflammation, in addition to MHC-I upregulation, do evoke an ER stress-response characterized by the increased expression of Grp94 and Grp75, respectively. The increase in the muscle Grp75 level in patients showing occasional immunoreactivity for sarcolemmal MHC-I might be considered further as a broader indicator of idiopathic inflammatory myopathy.

A transient antioxidant stress response accompanies the onset of disuse atrophy in human skeletal muscle

It is presently unknown whether oxidative stress increases in disused skeletal muscle in humans. Markers of oxidative stress were investigated in biopsies from the vastus lateralis muscle, collected from healthy subjects before [time 0 (T0)], after 1 wk (T8), and after 5 wk (T35) of bed rest. An 18% decrease in fiber cross-sectional area was detected in T35 biopsies (P<0.05). Carbonylation of muscle proteins significantly increased about twofold at T35 (P<0.02) and correlated positively with the decrease in fiber cross-sectional area (P=0.04). Conversely, T8 biopsies showed a significant increase in protein levels of heme oxygenase-1 and glucose-regulated protein-75 (Grp75)/mitochondrial heat shock protein-70, two stress proteins involved in the antioxidant defense (P<0.05). Heme oxygenase-1 increase, which involved a larger proportion of slow fibers compared with T0, appeared blunted in T35 biopsies. Grp75 protein level increased threefold in T8 biopsies and localized especially in slow fibers (P<0.025), to decrease significantly in T35 biopsies (P<0.05). Percent change in Grp75 levels positively correlated with fiber cross-sectional area (P=0.01). Parallel investigations on rat soleus muscles, performed after 1-15 days of hindlimb suspension, showed that Grp75 protein levels significantly increased after 24 h of unloading (P = 0.02), i.e., before statistically significant evidence of muscle atrophy, to decrease thereafter in relation to the degree of muscle atrophy (P=0.03). Therefore, in humans as in rodents, disuse muscle atrophy is characterized by increased protein carbonylation and by the blunting of the antioxidant stress response evoked by disuse.

Contribution of IL-6 to the Hsp72, Hsp25, and alphaB-crystallin [corrected] responses to inflammation and exercise training in mouse skeletal and cardiac muscle

The heat shock proteins (Hsps) Hsp72, Hsp25, and alphaB-crystallin (alphaB C) [corrected]may protect tissues during exercise and/or inflammatory insults; however, no studies have investigated whether exercise training increases both basal and inflammation-induced expression of these Hsps in skeletal or cardiac muscle. IL-6 is produced by muscle during both exercise and inflammation and has been shown to modulate Hsp expression. These studies tested the hypothesis that voluntary wheel running (RW) increases basal and inflammation-induced Hsp72, Hsp25, and alphaB C [corrected] protein through an IL-6-dependent mechanism. We compared Hsp72, Hsp25, alphaB C, [corrected] and IL-6 protein levels 4 h after systemic inflammation induced by lipopolysaccharide (LPS) in skeletal and cardiac muscles of wild-type (IL-6(+/+)) and IL-6 deficient (IL-6(-/-)) mice after 2 wk of RW or normal cage activity (Sed). LPS significantly increased skeletal Hsp72 and Hsp25 relative to saline in Sed IL-6(+/+), but not IL-6(-/-) mice. LPS increased Hsp72 relative to saline in Sed IL-6(+/+) cardiac muscle. RW increased basal Hsp72, Hsp25, and alphaB C [corrected] in skeletal muscle in IL-6(+/+) and IL-6(-/-) mice. However, LPS was not associated with increases in any Hsp in RW IL-6(+/+) or IL-6(-/-) mice. LPS increased IL-6 protein in skeletal muscle and plasma in Sed and RW groups, with a significantly greater response in RW. The major results provide the first in vivo evidence that the absence of IL-6 is associated with reduced skeletal muscle Hsp72 and Hsp25 responses to LPS, but that IL-6 is not required for exercise-induced Hsp upregulation in skeletal or cardiac muscle.

The effect of 15 consecutive days of heat-exercise acclimation on heat shock protein 70

The purpose of this study was to investigate the alterations in serum heat shock protein (Hsp) 70 levels during a 15-consecutive-day intermittent heat-exercise protocol in a 29-year-old male ultra marathon runner. Heat acclimation, for the purpose of physical activities in elevated ambient temperatures, has numerous physiological benefits including mechanisms such as improved cardiac output, increased plasma volume and a decreased core temperature (T (c)). In addition to the central adaptations, the role of Hsp during heat acclimation has received an increasing amount of attention. The acclimation protocol applied was designed to correspond with the athlete's tapering period for the 2007 Marathon Des Sables. The subject (VO(2)max = 50.7 ml.kg(-1).min(-1), peak power output [PPO] = 376 W) cycled daily for 90 min at a workload corresponding to 50% of VO(2)max in a temperature-controlled room (average WBGT = 31.9 +/- 0.9 degrees C). Venous blood was sampled before and after each session for measurement of serum osmolality and serum Hsp70. In addition, T (c), heart rate (HR) and power output (PO) was measured throughout the 90 min to ensure that heat acclimation was achieved during the 15-day period. The results show that the subject was successfully heat acclimated as seen by the lowered HR at rest and during exercise, decreased resting and exercising T (c) and an increased PO. The heat exercise resulted in an initial increase in Hsp70 concentrations, known as thermotolerance, and the increase in Hsp70 after exercise was inversely correlated to the resting values of Hsp70 (Spearman's rank correlation = -0.81, p < 0.01). Furthermore, the 15-day heat-exercise protocol also increased the basal levels of Hsp70, a response different from that of thermotolerance. This is, as far as we are aware, the first report showing Hsp70 levels during consecutive days of intermittent heat exposure giving rise to heat acclimation. In conclusion, a relatively longer heat acclimation protocol is suggested to obtain maximum benefit of heat acclimation inclusive of both cellular and systemic adaptations.

Inducible heat shock protein 70 and its role in preconditioning and exercise

Heat shock proteins (Hsp) are well known to be expressed in response to a range of cellular stresses. They are known to convey protection against protein denaturation and a subsequent immediate stress. Inducible heat shock protein 70 (Hsp70) is among the most studied of these stress proteins and its role and function are discussed here in terms of thermal and in particular exercise preconditioning. Preconditioning has been shown to confer cellular protection via expression Hsp, which may be of benefit in preventing protein damage following subsequent periods of exercise. Many studies have used animal models to gather data on Hsp70 and these and the most recent human studies are discussed.

Maximal eccentric exercise induces a rapid accumulation of small heat shock proteins on myofibrils and a delayed HSP70 response in humans

In this study the stress protein response to unaccustomed maximal eccentric exercise in humans was investigated. Eleven healthy males performed 300 maximal eccentric actions with the quadriceps muscle. Biopsies from vastus lateralis were collected at 30 min and 4, 8, 24, 96, and 168 h after exercise. Cellular regulation and localization of heat shock protein (HSP) 27, alpha B-crystallin, and HSP70 were analyzed by immunohistochemistry, ELISA technique, and Western blotting. Additionally, mRNA levels of HSP27, alpha B-crystallin, and HSP70 were quantified by Northern blotting. After exercise (30 min), 81 +/- 8% of the myofibers showed strong HSP27 staining (P < 0.01) that gradually decreased during the following week. alpha B-Crystallin mimicked the changes observed in HSP27. After exercise (30 min), the ELISA analysis showed a 49 +/- 13% reduction of the HSP27 level in the cytosolic fraction (P < 0.01), whereas Western blotting revealed a 15-fold increase of the HSP27 level in the myofibrillar fraction (P < 0.01). The cytosolic HSP70 level increased to 203 +/- 37% of the control level 24 h after exercise (P < 0.05). After 4 days, myofibrillar-bound HSP70 had increased approximately 10-fold (P < 0.01) and was accompanied by strong staining on cross sections. mRNA levels of HSP27, alpha B-crystallin, and HSP70 were all elevated the first day after exercise (P < 0.01); HSP70 mRNA showed the largest increase (20-fold at 8 h). HSP27 and alpha B-crystallin seemed to respond immediately to maximal eccentric exercise by binding to cytoskeletal/myofibrillar proteins, probably to function as stabilizers of disrupted myofibrillar structures. Later, mRNA and total HSP protein levels, especially HSP70, increased, indicating that HSPs play a role in skeletal muscle recovery and remodeling/adaptation processes to high-force exercise.

Modulation of HSP25 and TNF-alpha during the early stages of functional overload of a rat slow and fast muscle

Early events in response to abrupt increases in activation and loading with muscle functional overload (FO) are associated with increased damage and inflammation. Heat shock protein 25 (HSP25) may protect against these stressors, and its expression can be regulated by muscle loading and activation. The purpose of this study was to investigate the responses of HSP25, phosphorylated HSP25 (pHSP25), and tumor necrosis factor-alpha (TNF-alpha) during FO of the slow soleus and fast plantaris. We compared the HSP25 mRNA, HSP25 protein, pHSP25, and TNF-alpha responses in the soleus and plantaris after 0.5, 1, 2, 3, and 7 days of FO. HSP25 and pHSP25 were quantified in soluble and insoluble fractions. HSP25 mRNA increased immediately in both muscles and decreased with continued FO. However, HSP25 mRNA levels were consistently higher in the muscles of FO than control rats. In the soluble fraction, HSP25 increased in the plantaris after 2-7 days of FO with the greatest response at 3 and 7 days. The pHSP25 response to FO was greater in the plantaris than soleus at all points in the soluble fraction and at 0.5 days in the insoluble fraction. TNF-alpha levels in the plantaris, but not soleus, were higher than control at 0.5-2 days of FO. This may have contributed to the greater FO response in pHSP25 in the plantaris than soleus as TNF-alpha increased pHSP25 in C2C12 myotubes. These results suggest that the initial responses of pHSP25 and TNF-alpha to mechanical stress and inflammation associated with FO are greater in a fast than slow extensor muscle.