The transport profile of cytokines in epidermal equivalents subjected to mechanical loading

The use of a protein network analysis to explore the complexity of early skin inflammation after oronasal mask application- A pilot study

Medical devices, such as non-invasive ventilation masks, save lives in health care settings but can be a cause of tissue injuries due to the pressure and shear loads on skin and soft tissue. These pressure injuries could be painful for the individual and cause a significant economic impact on healthcare providers. In the etiology of device related pressure ulcers, inflammation plays an important role. However, the exact nature and timing of inflammatory biomarker upregulation is still unknown in the early stages of skin damage. This study aimed to explore the inflammatory profile of vulnerable skin sites following non-invasive mask application on a convenience sample of eleven hospital patients. Seventy-one inflammatory proteins were explored from sebum sampled at the skin surface after oronasal mask application. A multivariate analysis to investigate differences between loaded and control site was conducted, with a protein network analysis used to explore interactions in the early inflammation. The study revealed that 21 cytokines and chemokines were important for the separation between loaded and control site. These proteins were associated with remodeling of tissue, vascular wound healing and/or cell death.

The role of proinflammatory cytokines in the detection of early pressure ulcer development: a systematic review

OBJECTIVE

Pressure ulcers (PUs) commonly occur over bony prominences and are notoriously difficult to treat. Proinflammatory cytokines are substances that initiate the inflammatory process preceding PU development. The aim of this review was to assess whether the increased presence of proinflammatory cytokines could potentially be used as an early detection system for PU development.

METHOD

A systematic search of publications using MEDLINE, CINAHL, and Cochrane databases was conducted in August 2020. Data were extracted and a narrative synthesis was undertaken. The evidence-based librarianship (EBL) checklist assessed the methodological quality of the included studies. The systematic review included original research studies, prospective design, and human studies written in English. Retrospective studies, animal studies, conference papers, opinion papers and qualitative methodology were excluded. No restrictions on the date of publication and study setting were applied.

RESULTS

The six studies included were conducted between 2015 and 2019, 50% (n=3) used an experimental study design. The mean sample size was 15 participants (standard deviation=1.72). A total of seven proinflammatory cytokines were analysed. Statistically significant differences were found among inflammatory mediators. Overall results showed that the concentration of interleukin (IL)-1α significantly increased in each study. The EBL score varied between 77-88%. In total, 100% (n=6) of the studies scored ≥75%, reflecting validity.

CONCLUSION

It is not yet certain that monitoring proinflammatory cytokines represents a noninvasive method that could potentially direct preventative measures to those who are identified as at high risk for developing PUs. IL-1α potentially may be elevated for other health conditions, not just PUs. Future studies are therefore recommended.

Biomarkers for the early detection of pressure injury: A systematic review and meta-analysis

BACKGROUND

Pressure injury imposes a significant burden for patients and healthcare systems and the majority of pressure injuries are preventable. The early identification of pressure injury is critical for its prevention. As an objective measure, biomarkers have preliminarily shown the potential to identify individuals at risk for developing pressure injury before it is visually observed to occur. However, these results have not been synthesized.

OBJECTIVE

To assess and synthesise the predictive effect of different biomarkers in the early detection of pressure injury formation.

DESIGN

A systematic review and meta-analysis.

DATA SOURCES

PubMed, EMBASE, CINAHL Complete and the Cochrane Library were comprehensively searched for articles up to June 2021. No restrictions were applied to study design type, language, country, race or date of publication.

REVIEW METHODS

Two reviewers independently extracted data from all original eligible studies using a specified data extraction form, resolved disagreements through discussion and the involvement of an additional reviewer. Methodological quality of all included studies was independently appraised by two authors with the Joanna Briggs Institute (JBI) Critical Appraisal Checklist and the Newcastle-Ottawa Quality Assessment Scale (NOS). Heterogeneity of each study was estimated using the I² statistic, and the data was synthesized using StataSE15.

RESULTS

Eight observational studies involving 10595 participants were included. The overall pooled area under curve (AUC) and the 95% confidence intervals (CIs) of Serum albumin (Alb) was 0.66(0.62-0.70), and the Serum haemoglobin (Hb) was 0.67(0.60-0.74). The AUC and 95% CI of C-reactive protein (CRP) was 0.62(0.50-0.74), Braden score was 0.56 (0.429-0.691), Waterlow score was 0.729(0.654-0.803), Alb with Waterlow was 0.741(0.694-0.787), and the combination of Hb, CRP, Alb, Age and Gender was 0.79(0.682-0.898). Besides, the chemokine interferon-γ-induced protein of 10kd/CXCL10, cytokine interferon-α, tumor necrosis factor-alpha (TNF-α), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-15 (IL-15) and combination of creatine kinase (CK), myoglobin (Mb), heart-type fatty acid binding protein (H-FABP) and CRP may prove potential for detecting pressure injury.

CONCLUSION

The findings suggest the combination of Hb, CRP, Alb, Age and Gender is superior to other biomarkers. However, the predictive effect of biomarkers needs to be confirmed by more researches and patient-level data.

Traveling wave of inflammatory response to regulate the expansion or shrinkage of skin erythema

Many skin diseases show circular red lesions on the skin, called erythema. Erythema is characterized by the expansion of its circular area solely from local stimulation. A pathological inflammatory response caused by the stimulation persistently increases inflammatory mediators in the dermis, whereas a normal inflammatory response transiently increases mediators, resulting in the shrinkage of the erythema. Although the diffusion of mediators theoretically reproduces the expansion, how the inflammatory response expands or shrinks the erythema remains unknown. A possibility is positive feedback, which affects mediator production and can generate two distinct stable states (i.e., inflamed and noninflamed), referred to as bistability. Bistability causes a state transition either from the noninflamed to inflamed state or the reverse direction by suprathreshold stimulation. Additionally, the diffusion selectively causes state transition in either direction, resulting in spatial spread of the transited state, known as the traveling wave. Therefore, we hypothesize that the traveling wave of the inflammatory response can account for both the expansion and shrinkage. Using a reaction-diffusion model with bistability, we theoretically show a possible mechanism in which the circular inflamed area expands via the traveling wave from the noninflamed to the inflamed state. During the expansion, the boundary between the inflamed and noninflamed areas moves at a constant velocity while maintaining its concentration gradient. Moreover, when the positive feedback is weak, the traveling wave selectively occurs from the inflamed to noninflamed state, shrinking the inflamed area. Whether the inflamed area expands or shrinks is mainly controlled by the balance of mediator concentration between the noninflamed and inflamed states, relative to the threshold. The traveling wave of the inflammatory response provides an experimentally testable framework for erythema expansion and shrinkage, thereby contributing to the development of effective treatments, including probiotics.

The Effect of Shear Force on Skin Viability in Patients with Type 2 Diabetes

BACKGROUND

Shear is a major risk factor in the development of diabetic foot ulcers, but its effect on the skin of patients with type 2 diabetes mellitus (DM) remains to be elucidated. The aim was to determine skin responses to shear in DM patients with and without diabetic polyneuropathy (DNP).

METHODS

The forearm skin was loaded with 14.5 N shear (+2.4 kPa pressure) and with 3.5 kPa pressure for 30 minutes in 10 type 2 DM patients without DNP, 10 type 2 DM patients with DNP, and 10 healthy participants. A Sebutape collected IL-1α (measure of tissue damage). A laser Doppler flowmeter measured cutaneous blood cell flux (CBF) as a measure of the reactive hyperaemic skin response.

FINDINGS

Reactive hyperaemia and IL-1α release was significantly increased after shear loading in all three groups and was higher compared to the responses to pressure loading. The reactive hyperaemic response after shear loading was impaired in patients with type 2 DM compared to healthy participants but did not differ between patients with and without DNP. The reactive hyperaemic response was negatively correlated with the blood glucose level but did not correlate with the DNP severity score.

INTERPRETATION

Shear is important in the development of tissue damage, but the reparative responses to shear are impaired in patients with type 2 DM. DNP was not associated with altered skin responses, suggesting that the loss of protective sensation to sense shear to skin remains a key factor in the development of diabetic foot ulcers in patients with DNP.

An advanced magnetic resonance imaging perspective on the etiology of deep tissue injury

Early diagnosis of deep tissue injury remains problematic due to the complicated and multifactorial nature of damage induction and the many processes involved in damage development and recovery. In this paper, we present a comprehensive assessment of deep tissue injury development and remodeling in a rat model by multiparametric magnetic resonance imaging (MRI) and histopathology. The tibialis anterior muscle of rats was subjected to mechanical deformation for 2 h. Multiparametric in vivo MRI, consisting of T2, T2*, mean diffusivity (MD), and angiography measurements, was applied before, during, and directly after indentation as well as at several time points during a 14-day follow-up. MRI readouts were linked to histological analyses of the damaged tissue. The results showed dynamic change in various MRI parameters, reflecting the histopathological status of the tissue during damage induction and repair. Increased T2 corresponded with edema, muscle cell damage, and inflammation. T2* was related to tissue perfusion, hemorrhage, and inflammation. MD increase and decrease was reported on the tissue’s microstructural integrity and reflected muscle degeneration and edema as well as fibrosis. Angiography provided information on blockage of blood flow during deformation. Our results indicate that the effects of a single damage-causing event of only 2 h of deformation were present up to 14 days. The initial tissue response to deformation, as observed by MRI, starts at the edge of the indentation. The quantitative MRI readouts provided distinct and complementary information on the extent, temporal evolution, and microstructural basis of deep tissue injury-related muscle damage.

NEW & NOTEWORTHY We have applied a multiparametric MRI approach linked to histopathology to characterize damage development and remodeling in a rat model of deep tissue injury. Our approach provided several relevant insights in deep tissue injury. Response to damage, as observed by MRI, started at some distance from the deformation. Damage after a single indentation period persisted up to 14 days. The MRI parameters provided distinct and complementary information on the microstructural basis of the damage.

Investigating the effects of cervical collar design and fit on the biomechanical and biomarker reaction at the skin

Background

Research has shown that up to 33% of pressure ulcers (PUs) acquired in hospitals result from the application of a medical device. Cervical collars (C-collars) have been implicated in causing PUs, due to the mechanical force they apply to the skin. In order to improve our understanding of collar-related PUs, the present study aimed to assess the biomechanical, biochemical, and microclimate effects of C-collar design and fitting tension.

Methods

A cohort of 15 healthy volunteers was fit with two different C-collars according to the manufacturer guidelines. Two further collar tensions were also defined as loose and tight for each device. Each collar condition was applied for 15 minutes, with a 10 minute refractory period. Measurements at the device–skin interface included interface pressures, inflammatory biomarkers, microclimate, range of cervical motion, and comfort scores.

Results

The interface pressures at each tissue site increased monotonically with greater collar tension (p<0.01), irrespective of collar design. Biomarker analysis revealed that inflammatory cytokines (IL-1a) were elevated during collar application, with the highest increase during the tight fit condition, representing over a fourfold increase from unloaded conditions. Regardless of collar tension or type, there was an increase in temperature 1.5°C ±0.8°C compared to baseline values. Range of motion significantly decreased with greater strap tension (p<0.05), with an associated increase in discomfort.

Conclusion

The present findings revealed that increasing C-collar tensions caused elevated contact pressures at the device–skin interface, with a corresponding inflammatory response at the skin. These peak contact pressures were highest at the occiput, corresponding with reported PU locations. Devices should be designed to uniformly distribute pressures, and appropriate guidance is needed for their application.

Molecular finds of pressure ulcer: A bioinformatics approach in pressure ulcer

BACKGROUND

Understanding the biological processes underlying Pressure Ulcer (PU) is an important strategy to identify new molecular targets. Bioinformatics has emerged as an important screening tool for a broad range of diseases.

OBJECTIVE

This study aim of the current study is to investigate the protein-protein interaction in the PU context by bioinformatics.

METHODS

We performed a search in gene databases, and bioinformatics algorithms were used to generate molecular targets for PU based in silico investigation. Interactions networks between protein-coding genes were built and compared to skin.

RESULTS

TNFA, MMP9, and IL10 genes have higher disease-related connectivity than a connectivity general global. MAGOH, UBC, and PTCH1 as were leader genes related to skin. Ontological analysis demonstrated different mechanisms associated, such as response to oxidase stress.

CONCLUSION

TNFA, MMP9, and IL10 are possible therapeutic targets for pressure ulcer. Additional investigation of cell post-transcriptional machinery should be investigated in PU.

Investigating the effects of strap tension during non-invasive ventilation mask application: a combined biomechanical and biomarker approach

Non-invasive ventilation is commonly used for respiratory support. However, in some cases, mask application can cause pressure ulcers to specific features of the face, resulting in pain and reduced quality of life for the individual. This study investigated the effects of mask strap tension on the biomechanical and biomarker responses at the skin interface. Healthy participants (n = 13) were recruited and assigned two different masks in a random order, which were fitted with three strap conditions representing increments of 5 mm to increase tension. Masks were worn for 10 minutes at each tension followed by a 10-minute refractory period. Assessment at the device–skin interface included measurements of pressures at the nose and cheeks, temperature and humidity, a selection of inflammatory cytokine concentrations collected from sebum and scores of comfort. The results indicated significantly higher interface pressures at the bridge of the nose compared to the cheeks for both masks (p < 0.05), with nasal interface pressures significantly increasing with elevated strap tension (p < 0.05). One inflammatory cytokine, IL-1α, increased following mask application at the highest tension, with median increases from baselines ranging from 21 to 33%. The other cytokines revealed a less consistent trend with strap tension. The participants reported statistically greater discomfort during elevated strap tension. Temperature and humidity values under the mask were elevated from ambient conditions, although no differences were observed between mask type or strap tension. The bony prominence on the bridge of the nose represented a vulnerable area of skin during respiratory mask application. This study has shown that mask strap tension has a significant effect on the pressure exerted on the nose. This can result in discomfort and an inflammatory response at the skin surface. Further studies are required to investigate respiratory mask application for appropriate individuals with comorbidities.

An ex vivo porcine skin model to evaluate pressure-reducing devices of different mechanical properties used for pressure ulcer prevention

Pressure ulcers are complex wounds caused by pressure- and shear-induced trauma to skin and underlying tissues. Pressure-reducing devices, such as dressings, have been shown to successfully reduce pressure ulcer incidence, when used in adjunct to pressure ulcer preventative care. While pressure-reducing devices are available in a range of materials, with differing mechanical properties, understanding of how a material's mechanical properties will influence clinical efficacy remains limited. The aim of this study was to establish a standardized ex vivo model to allow comparison of the cell protection potential of two gel-like pressure-reducing devices with differing mechanical properties (elastic moduli of 77 vs. 35 kPa). The devices also displayed differing energy dissipation under compressive loading, and resisted strain differently under constant load in compressive creep tests. To evaluate biological efficacy we employed a new ex vivo porcine skin model, with a confirmed elastic moduli closely matching that of human skin (113 vs. 119 kPa, respectively). Static loads up to 20 kPa were applied to porcine skin ex vivo with subsequent evaluation of pressure-induced cell death and cytokine release. Pressure application alone increased the percentage of epidermal apoptotic cells from less than 2% to over 40%, and increased cellular secretion of the pro-inflammatory cytokine TNF-alpha. Co-application of a pressure-reducing device significantly reduced both cellular apoptosis and cytokine production, protecting against cellular damage. These data reveal new insight into the relationship between mechanical properties of pressure-reducing devices and their biological effects. After appropriate validation of these results in clinical pressure ulcer prevention with all tissue layers present between the bony prominence and external surface, this ex vivo porcine skin model could be widely employed to optimize design and evaluation of devices aimed at reducing pressure-induced skin damage.

A new method to evaluate the effects of shear on the skin

Currently, pressure ulcer preventive strategies focus mainly on pressure redistribution. Little attention is paid to reduce the harmful effects of shear-force, because little is known about pathophysiological aspects of shear-force. Even today, no method to measure the effects of shear-force on the skin is available. Therefore, the aim of this study was to investigate the response to shear-forces in terms of analyzing a noninvasive biomarker and reactive hyperemic parameter measured at the skin of healthy participants. A physical model was developed to produce a combination of pressure and shear or pressure alone on the skin. Ten healthy male participants were included and pressure (3.9 kPa) and a combined loading of pressure and shear (2.4 kPa + 14.5 N) was applied at the volar aspect of the forearms for 15 and 30 minutes. A Sebutape sample was used to collect IL-1α and total protein (TP) noninvasively. The reactive hyperemic parameter was derived from a laser Doppler flowmeter. The increase in IL-1α/TP-ratio after a combined loading of pressure and shear for 30 minutes of 6.2 ± 2.5 was significantly higher compared with all other test conditions (p < 0.05). The increase in cutaneous blood cell flux was already significantly higher when a combined loading of pressure and shear was applied for 15 minutes compared with pressure alone. These results shows that the IL-1α/TP-ratio and cutaneous blood cell flux can be used as robust measures of the effect of shear-force on skin in humans. Therefore, this model can be used to evaluate materials aimed at the reduction of shear.

Pressure ulcers in the hospitalized neonate: rates and risk factors

Pressure ulcers (PU) are serious, reportable events causing pain, infection and prolonged hospitalization, particularly among critically ill patients. The literature on PUs in neonates is limited. The objective was to determine the etiology, severity and influence of gestational age on PUs among hospitalized infants. A two-year prospective study was conducted among 741 neonatal intensive care patients over 31,643 patient-days. Risk factors were determined by comparing the characteristics of infants who developed PUs with those who did not. There were 1.5 PUs per 1000 patient days with 1.0 PU per 1000 days in premature infants and 2.7 per 1000 days in term infants. The number of PUs associated with devices was nearly 80% overall and over 90% in premature infants. Infants with PUs had longer hospitalizations and weighed more than those who did not. Infants with device-related PUs were younger, of lower gestational age and developed the PU earlier than patients with PUs due to conventional pressure. The time to PU development was longer in prematurely born versus term infants. Hospitalized neonates are susceptible to device-related injury and the rate of stage II injury is high. Strategies for early detection and mitigation of device-related injury are essential to prevent PUs.

Spatiotemporal evolution of erythema migrans, the hallmark rash of Lyme disease

To elucidate pathogen-host interactions during early Lyme disease, we developed a mathematical model that explains the spatiotemporal dynamics of the characteristic first sign of the disease, a large (≥5-cm diameter) rash, known as an erythema migrans. The model predicts that the bacterial replication and dissemination rates are the primary factors controlling the speed that the rash spreads, whereas the rate that active macrophages are cleared from the dermis is the principle determinant of rash morphology. In addition, the model supports the clinical observations that antibiotic treatment quickly clears spirochetes from the dermis and that the rash appearance is not indicative of the efficacy of the treatment. The quantitative agreement between our results and clinical data suggest that this model could be used to develop more efficient drug treatments and may form a basis for modeling pathogen-host interactions in other emerging infectious diseases.

Effect of local cooling on pro-inflammatory cytokines and blood flow of the skin under surface pressure in rats: feasibility study

The primary purpose of this feasibility study was to establish a correlation between pro-inflammatory cytokine accumulation and severity of tissue damage during local pressure with various temperatures. The secondary purpose was to compare skin blood flow patterns for assessing the efficacy of local cooling on reducing skin ischemia under surface pressure. Eight Sprague-Dawley rats were assigned to two protocols, including pressure with local cooling (Δt = -10 °C) and pressure with local heating (Δt = 10 °C). Pressure of 700 mmHg was applied to the right trochanter area of rats for 3 h. Skin perfusion quantified by laser Doppler flowmetry and TNF-∗ and IL-1β levels were measured. Our results showed that TNF-α concentrations were increased more significantly with local heating than with local cooling under pressure whereas IL-1β did not change. Our results support the notion that weight bearing soft tissue damage may be reduced through temperature modulation and that non-invasive perfusion measurements using laser Doppler flowmetry may be capable of assessing viability. Furthermore, these results show that perfusion response to loading pressure may be correlated with changes in local pro-inflammatory cytokines. These relationships may be relevant for the development of cooling technologies for reducing risk of pressure ulcers.

Deep tissue injury in development of pressure ulcers: a decrease of inflammasome activation and changes in human skin morphology in response to aging and mechanical load

Molecular mechanisms leading to pressure ulcer development are scarce in spite of high mortality of patients. Development of pressure ulcers that is initially observed as deep tissue injury is multifactorial. We postulate that biomechanical forces and inflammasome activation, together with ischemia and aging, may play a role in pressure ulcer development. To test this we used a newly-developed bio-mechanical model in which ischemic young and aged human skin was subjected to a constant physiological compressive stress (load) of 300 kPa (determined by pressure plate analyses of a person in a reclining position) for 0.5–4 hours. Collagen orientation was assessed using polarized light, whereas inflammasome proteins were quantified by immunoblotting. Loaded skin showed marked changes in morphology and NLRP3 inflammasome protein expression. Sub-epidermal separations and altered orientation of collagen fibers were observed in aged skin at earlier time points. Aged skin showed significant decreases in the levels of NLRP3 inflammasome proteins. Loading did not alter NLRP3 inflammasome proteins expression in aged skin, whereas it significantly increased their levels in young skin. We conclude that aging contributes to rapid morphological changes and decrease in inflammasome proteins in response to tissue damage, suggesting that a decline in the innate inflammatory response in elderly skin could contribute to pressure ulcer pathogenesis. Observed morphological changes suggest that tissue damage upon loading may not be entirely preventable. Furthermore, newly developed model described here may be very useful in understanding the mechanisms of deep tissue injury that may lead towards development of pressure ulcers.

Soft-tissue alterations following exposure to tooth-whitening agents

BACKGROUND

Tooth-whitening agents are widely used, either as self-application products or under the supervision of a dentist. These products may be associated with transient gross morphologic changes in oral soft tissues. However, their potential effects on human keratinocytes and fibroblasts in a stratified squamous epithelium have yet to be elucidated.

METHODS

In this study, three-dimensional human tissue equivalents are exposed to varying concentrations of tooth-whitening agents for increasing time periods. Tissue alterations are investigated in terms of morphology, proliferation, apoptosis, and protein expression.

RESULTS

All whitening agents tested altered tissue morphology, induced proliferation of basal keratinocytes, and caused apoptosis of cells in all epithelial strata. In addition, whitening agents induced alterations in the expression of cytokines that are linked to inflammation.

CONCLUSIONS

These results suggest that whitening agents may induce similar changes in vivo and that these products should be used for limited periods of time or under the supervision of a dental professional.

New concepts in the prevention of pressure sores

Pressure sores are a serious, and costly, complication for many patients with reduced mobility and sensation. Some populations, such as those with spinal cord injury (SCI), remain at high risk throughout their lifetime. Prevention is highly preferable and while the concept is readily definable, it is much more challenging to develop valid preventative measures. Subjective and objective approaches to risk factor assessment before pressure sores develop are reviewed, including risk status scales and emerging techniques to assess deep tissue injury. Devices to prevent pressure sores have traditionally focused on pressure-relieving cushions and mattresses. Technological advances being applied in the development of new pressure sore prevention devices are presented. Clinical evidence-based practice is integral to pressure sore prevention. Comprehensive assessment must include evaluation of systemic diseases, anatomical and physiological factors, together with environmental and psychosocial factors, which can all contribute to pressure sore development. Extrinsic factors need to be considered in conjunction with intrinsic tissue health factors and are reviewed together with an evaluation of currently available clinical practice guidelines. This chapter presents the broad diversity of factors associated with pressure sore development and highlights the need for an interdisciplinary team approach in order to maximize successful prevention of pressure sores.

Opposing responses of apoptosis and autophagy to moderate compression in skeletal muscle

AIM

The molecular mechanism that contributes to the pathogenesis of deep pressure ulcer remains to be elucidated. This study tested the hypotheses that: (1) apoptosis and autophagy are activated in compression-induced muscle pathology and (2) apoptotic and autophagic changes precede pathohistological changes in skeletal muscle in response to prolonged moderate compression.

METHODS

  Adult Sprague-Dawley rats were subjected to an experimental model of pressure-induced deep tissue injury. Static pressure of 100 mmHg was applied to an area of 1.5 cm(2) over the mid-tibialis region of right limb of rats for one single session of 6-h compression (1D) or two sessions of 6-h compression over two consecutive days with rats sacrificed one day (2D) or immediately after (2D-IM) the compression. The left uncompressed limb served as the intra-animal control. Muscle tissues underneath compression region were collected for analysis.

RESULTS

Our histological analysis indicated that pathohistological characteristics including rounding contour of myofibres and massive nuclei accumulation were apparently demonstrated in muscles of 2D and 2D-IM. In contrast, these pathohistological changes were generally not found in muscle following 1D. Apoptotic DNA fragmentation, terminal dUTP nick-end labelling index and caspase-3 protease activity were significantly elevated in compressed muscles of all groups. Caspase-9 enzymatic activity was found to be significantly increased in compressed muscles of 2D and 2D-IM whereas increase in caspase-8 activity was exclusively found in compressed muscle of 1D. According to our immunoblot analysis, FoxO3 was significantly reduced in compressed muscles of all groups whereas Beclin-1 was decreased only in 2D. LC3-I was significantly reduced in compressed muscles of all groups while LC3-II was decreased in 2D and 1D. No significant differences were found in the protein abundance of Akt and phospho-Akt in muscles among all groups.

CONCLUSION

These data demonstrate the opposing responses of apoptosis and autophagy to moderate compression in muscle. Moreover, our findings suggest that cellular changes in apoptosis and autophagy have already taken place in the very early stage in which apparent histopathology has yet to develop in the process of compression-induced muscle pathology.