Dataset Information

Caspase-3 regulation of diaphragm myonuclear domain during mechanical ventilation-induced atrophy.

ABSTRACT:

Rationale

Unloading the diaphragm via mechanical ventilation (MV) results in rapid diaphragmatic fiber atrophy. It is unknown whether the myonuclear domain (cytoplasmic myofiber volume/myonucleus) of diaphragm myofibers is altered during MV.

Objective

We tested the hypothesis that MV-induced diaphragmatic atrophy is associated with a loss of myonuclei via a caspase-3-mediated, apoptotic-like mechanism resulting in a constant myonuclear domain.

Methods

To test this postulate, Sprague-Dawley rats were randomly assigned to a control group or to experimental groups exposed to 6 or 12 h of MV with or without administration of a caspase-3 inhibitor.

Measurements and main results

After 12 h of MV, type I and type IIa diaphragm myofiber areas were decreased by 17 and 23%, respectively, and caspase-3 inhibition attenuated this decrease. Diaphragmatic myonuclear content decreased after 12 h of MV and resulted in the maintenance of a constant myonuclear domain in all fiber types. Both 6 and 12 h of MV resulted in caspase-3-dependent increases in apoptotic markers in the diaphragm (e.g., number of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling positive nuclei and DNA fragmentation). Caspase-3-dependent increases in apoptotic markers occurred after 6 h of MV, before the onset of myofiber atrophy.

Conclusions

Collectively, these data support the hypothesis that the myonuclear domain of diaphragm myofibers is maintained during prolonged MV and that caspase-3-mediated myonuclear apoptosis contributes to this process.

SUBMITTER: McClung JM

PROVIDER: S-EPMC1899279 | biostudies-literature | 2007 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Caspase-3 regulation of diaphragm myonuclear domain during mechanical ventilation-induced atrophy.

McClung Joseph M JM Kavazis Andreas N AN DeRuisseau Keith C KC Falk Darin J DJ Deering Melissa A MA Lee Youngil Y Sugiura Takao T Powers Scott K SK

American journal of respiratory and critical care medicine 20061102 2

<h4>Rationale</h4>Unloading the diaphragm via mechanical ventilation (MV) results in rapid diaphragmatic fiber atrophy. It is unknown whether the myonuclear domain (cytoplasmic myofiber volume/myonucleus) of diaphragm myofibers is altered during MV.<h4>Objective</h4>We tested the hypothesis that MV-induced diaphragmatic atrophy is associated with a loss of myonuclei via a caspase-3-mediated, apoptotic-like mechanism resulting in a constant myonuclear domain.<h4>Methods</h4>To test this postulate ...[more]

PMID: 17082496

Similar Datasets

Project description:Mechanical ventilation (MV) is a clinical tool providing adequate alveolar ventilation in patients that require respiratory support. Although a life-saving intervention for critically ill patients, prolonged MV results in the rapid development of inspiratory muscle weakness due to both diaphragmatic atrophy and contractile dysfunction; collectively known as "ventilator-induced diaphragm dysfunction" (VIDD). VIDD is a severe clinical problem because diaphragmatic weakness is a risk factor for difficulties in weaning patients from MV. Currently, no standard treatment to prevent VIDD exists. Nonetheless, growing evidence reveals that hydrogen sulfide (H2 S) possesses cytoprotective properties capable of protecting skeletal muscles against several hallmarks of VIDD, including oxidative damage, accelerated proteolysis, and mitochondrial damage. Therefore, we used an established animal model of MV to test the hypothesis that treatment with sodium sulfide (H2 S donor) will defend against VIDD. Our results confirm that sodium sulfide was sufficient to protect the diaphragm against both MV-induced fiber atrophy and contractile dysfunction. H2 S prevents MV-induced damage to diaphragmatic mitochondria as evidenced by protection against mitochondrial uncoupling. Moreover, treatment with sodium sulfide prevented the MV-induced activation of the proteases, calpain, and caspase-3 in the diaphragm. Taken together, these results support the hypothesis that treatment with a H2 S donor protects the diaphragm against VIDD. These outcomes provide the first evidence that H2 S has therapeutic potential to protect against MV-induced diaphragm weakness and to reduce difficulties in weaning patients from the ventilator. Study Highlights WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC? Mechanical ventilation (MV) results in diaphragm atrophy and contractile dysfunction, known as ventilator-induced diaphragm dysfunction (VIDD). VIDD is important because diaphragm weakness is a risk factor for problems in weaning patients from MV. Currently, no accepted treatment exists to protect against VIDD. Growing evidence reveals that hydrogen sulfide (H2 S) donors protect skeletal muscle against ischemia-reperfusion-induced injury. Nonetheless, it is unknown if treatment with a H2 S donor can protect against VIDD. WHAT QUESTION DID THIS STUDY ADDRESS? Can treatment with an H2 S donor protect against VIDD? WHAT DOES THIS STUDY ADD TO OUR KNOWLEDGE? This study provides the first evidence that treatment with a H2 S donor protects against VIDD. HOW MIGHT THIS CHANGE CLINICAL PHARMACOLOGY OR TRANSLATIONAL SCIENCE? These new findings provide the basis for further exploration of H2 S donors as a therapy to prevent VIDD and reduce the risk of problems in weaning patients from MV.

Project description:Previous workers have demonstrated that controlled mechanical ventilation results in diaphragm inactivity and elicits a rapid development of diaphragm weakness as a result of both contractile dysfunction and fiber atrophy. Limited data exist regarding the impact of pressure support ventilation, a commonly used mode of mechanical ventilation-that permits partial mechanical activity of the diaphragm-on diaphragm structure and function. We carried out the present study to test the hypothesis that high-level pressure support ventilation decreases the diaphragm pathology associated with CMV.Sprague-Dawley rats were randomly assigned to one of the following five groups:1) control (no mechanical ventilation); 2) 12 hrs of controlled mechanical ventilation (12CMV); 3) 18 hrs of controlled mechanical ventilation (18CMV); 4) 12 hrs of pressure support ventilation (12PSV); or 5) 18 hrs of pressure support ventilation (18PSV).We carried out the following measurements on diaphragm specimens: 4-hydroxynonenal-a marker of oxidative stress, active caspase-3 (casp-3), active calpain-1 (calp-1), fiber type cross-sectional area, and specific force (sp F). Compared with the control, both 12PSV and 18PSV promoted a significant decrement in diaphragmatic specific force production, but to a lesser degree than 12CMV and 18CMV. Furthermore, 12CMV, 18PSV, and 18CMV resulted in significant atrophy in all diaphragm fiber types as well as significant increases in a biomarker of oxidative stress (4-hydroxynonenal) and increased proteolytic activity (20S proteasome, calpain-1, and caspase-3). Furthermore, although no inspiratory effort occurs during controlled mechanical ventilation, it was observed that pressure support ventilation resulted in large decrement, approximately 96%, in inspiratory effort compared with spontaneously breathing animals.High levels of prolonged pressure support ventilation promote diaphragmatic atrophy and contractile dysfunction. Furthermore, similar to controlled mechanical ventilation, pressure support ventilation-induced diaphragmatic atrophy and weakness are associated with both diaphragmatic oxidative stress and protease activation.

Project description:Controlled mechanical ventilation (CMV) is associated with the development of diaphragm atrophy and contractile dysfunction, and respiratory muscle weakness is thought to contribute significantly to delayed weaning of patients. Therefore, therapeutic strategies for preventing these processes may have clinical benefit. The aim of the current study was to investigate the role of the Janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) signaling pathway in CMV-mediated diaphragm wasting and weakness in rats. CMV-induced diaphragm atrophy and contractile dysfunction coincided with marked increases in STAT3 phosphorylation on both tyrosine 705 (Tyr705) and serine 727 (Ser727). STAT3 activation was accompanied by its translocation into mitochondria within diaphragm muscle and mitochondrial dysfunction. Inhibition of JAK signaling during CMV prevented phosphorylation of both target sites on STAT3, eliminated the accumulation of phosphorylated STAT3 within the mitochondria, and reversed the pathologic alterations in mitochondrial function, reduced oxidative stress in the diaphragm, and maintained normal diaphragm contractility. In addition, JAK inhibition during CMV blunted the activation of key proteolytic pathways in the diaphragm, as well as diaphragm atrophy. These findings implicate JAK/STAT3 signaling in the development of diaphragm muscle atrophy and dysfunction during CMV and suggest that the delayed extubation times associated with CMV can be prevented by inhibition of Janus kinase signaling.-Smith, I. J., Godinez, G. L., Singh, B. K., McCaughey, K. M., Alcantara, R. R., Gururaja, T., Ho, M. S., Nguyen, H. N., Friera, A. M., White, K. A., McLaughlin, J. R., Hansen, D., Romero, J. M., Baltgalvis, K. A., Claypool, M. D., Li, W., Lang, W., Yam, G. C., Gelman, M. S., Ding, R., Yung, S. L., Creger, D. P., Chen, Y., Singh, R., Smuder, A. J., Wiggs, M. P., Kwon, O.-S., Sollanek, K. J., Powers, S. K., Masuda, E. S., Taylor, V. C., Payan, D. G., Kinoshita, T., Kinsella, T. M. Inhibition of Janus kinase signaling during controlled mechanical ventilation prevents ventilation-induced diaphragm dysfunction.

Project description:Diaphragmatic weakness, due to both atrophy and contractile dysfunction, is a well-documented response following prolonged mechanical ventilation. Evidence indicates that activation of the proteases calpain and caspase-3 is essential for mechanical ventilation-induced diaphragmatic weakness to occur. We tested the hypothesis that a regulatory cross-talk exists between calpain and caspase-3 in the diaphragm during prolonged mechanical ventilation. To test this prediction, we determined whether selective pharmacological inhibition of calpain would prevent activation of caspase-3 and conversely whether selective inhibition of caspase-3 would abate calpain activation.Animal study.University Research Laboratory.Female Sprague-Dawley rats.Animals were randomly divided into control or one of three 12-hr mechanical ventilation groups that were treated with/without a selective pharmacological protease inhibitor: 1) control, 2) mechanical ventilation, 3) mechanical ventilation with a selective caspase-3 inhibitor, and 4) mechanical ventilation with a selective calpain inhibitor.Compared to control, mechanical ventilation resulted in calpain and caspase-3 activation in the diaphragm accompanied by atrophy of type I, type IIa, and type IIx/IIb fibers. Independent inhibition of either calpain or caspase-3 prevented this mechanical ventilation-induced atrophy. Pharmacological inhibition of calpain prevented mechanical ventilation-induced activation of diaphragmatic caspase-3 and inhibition of caspase-3 prevented activation of diaphragmatic calpain. Furthermore, calpain inhibition also prevented the activation of caspase-9 and caspase-12, along with the cleavage of Bid to tBid, all upstream signals for caspase-3 activation. Lastly, caspase-3 inhibition prevented the mechanical ventilation-induced degradation of the endogenous calpain inhibitor, calpastatin.Collectively, these results indicate that mechanical ventilation-induced diaphragmatic atrophy is dependent on the activation of both calpain and caspase-3. Importantly, these findings provide the first experimental evidence in diaphragm muscle that calpain inhibition prevents the activation of caspase-3 and vice versa and caspase-3 inhibition prevents the activation of calpain. These findings support our hypothesis that a regulatory calpain/caspase-3 cross-talk exists whereby calpain can promote caspase-3 activation and active caspase-3 can enhance calpain activity in diaphragm muscle during prolonged mechanical ventilation.

Project description:BACKGROUND:Lung-protective ventilation (LPV) has been found to minimize the risk of ventilator-induced lung injury (VILI). However, whether LPV is able to diminish ventilator-induced diaphragm dysfunction (VIDD) remains unknown. This study was designed to test the hypothesis that LPV protects the diaphragm against VIDD. METHODS:Adult male Wistar rats received either conventional mechanical (tidal volume [VT]: 10 ml/kg, positive end-expiratory pressure [PEEP]: 2 cm H2O; CV group) or lung-protective (VT: 5 ml/kg, PEEP: 10 cm H2O; LPV group) ventilation for 12 h. Then, diaphragms and lungs were collected for biochemical and histological analyses. Transcriptome sequencing (RNA-seq) was performed to determine the differentially expressed genes in the diaphragms between groups. RESULTS:Our results suggested that LPV was associated with diminished pulmonary injuries and reduced oxidative stress compared with the effects of the CV strategy in rats. However, animals that received LPV showed increased protein degradation, decreased cross-sectional areas (CSAs) of myofibers, and reduced forces of the diaphragm compared with the same parameters in animals receiving CV (p < 0.05). In addition, the LPV group showed a higher level of oxidative stress in the diaphragm than the CV group (p < 0.05). Moreover, RNA-seq and western blots revealed that the peroxisome proliferator-activated receptor γ coactivator-1alpha (PGC-1α), a powerful reactive oxygen species (ROS) inhibitor, was significantly downregulated in the LPV group compared with its expression in the CV group (p < 0.05). CONCLUSIONS:Compared with the CV strategy, the LPV strategy did not protect the diaphragm against VIDD in rats. In contrast, the LPV strategy worsened VIDD by inducing oxidative stress together with the downregulation of PGC-1α in the diaphragm. However, further studies are required to determine the roles of PGC-1α in ventilator-induced diaphragmatic oxidative stress.

Project description:BackgroundMechanical ventilation is a life-saving intervention used to provide adequate pulmonary ventilation in patients suffering from respiratory failure. However, prolonged mechanical ventilation is associated with significant diaphragmatic weakness resulting from both myofiber atrophy and contractile dysfunction. Although several signaling pathways contribute to diaphragm weakness during mechanical ventilation, it is established that oxidative stress is required for diaphragmatic weakness to occur. Therefore, identifying the site(s) of mechanical ventilation- induced reactive oxygen species production in the diaphragm is important.ObjectiveThese experiments tested the hypothesis that elevated mitochondrial reactive oxygen species emission is required for mechanical ventilation-induced oxidative stress, atrophy, and contractile dysfunction in the diaphragm.DesignCause and effect was determined by preventing mechanical ventilation-induced mitochondrial reactive oxygen species emission in the diaphragm of rats using a novel mitochondria-targeted antioxidant (SS-31).InterventionsNone.Measurements and main resultsCompared to mechanically ventilated animals treated with saline, animals treated with SS-31 were protected against mechanical ventilation-induced mitochondrial dysfunction, oxidative stress, and protease activation in the diaphragm. Importantly, treatment of animals with the mitochondrial antioxidant also protected the diaphragm against mechanical ventilation-induced myofiber atrophy and contractile dysfunction.ConclusionsThese results reveal that prevention of mechanical ventilation-induced increases in diaphragmatic mitochondrial reactive oxygen species emission protects the diaphragm from mechanical ventilation-induced diaphragmatic weakness. This important new finding indicates that mitochondria are a primary source of reactive oxygen species production in the diaphragm during prolonged mechanical ventilation. These results could lead to the development of a therapeutic intervention to impede mechanical ventilation-induced diaphragmatic weakness.

Project description:ObjectivesAlthough mechanical ventilation is a life-saving measure for patients in respiratory failure, prolonged mechanical ventilation results in diaphragmatic weakness attributable to fiber atrophy and contractile dysfunction. Therefore, identifying the signaling pathways responsible for mechanical ventilation-induced diaphragmatic weakness is important. In this context, it is established that oxidative stress is required for mechanical ventilation-induced diaphragmatic weakness to occur. Numerous redox-sensitive signaling pathways exist in muscle including the transcription factor nuclear factor-κB. Although it has been suggested that nuclear factor-κB contributes to proteolytic signaling in inactivity-induced atrophy in locomotor muscles, the role that nuclear factor-κB plays in mechanical ventilation-induced diaphragmatic weakness is unknown. We tested the hypothesis that nuclear factor-κB activation plays a key signaling role in mechanical ventilation-induced diaphragmatic weakness and that oxidative stress is required for nuclear factor-κB activation.DesignCause and effect was determined by independently treating mechanically ventilated animals with either a specific nuclear factor-κB inhibitor (SN50) or a clinically relevant antioxidant (curcumin).Measurements and main resultsInhibition of nuclear factor-κB activity partially attenuated both mechanical ventilation-induced diaphragmatic atrophy and contractile dysfunction. Further, treatment with the antioxidant curcumin prevented mechanical ventilation-induced activation of nuclear factor-κB in the diaphragm and rescued the diaphragm from both mechanical ventilation-induced atrophy and contractile dysfunction.ConclusionsCollectively, these findings support the hypothesis that nuclear factor-κB activation plays a significant signaling role in mechanical ventilation-induced diaphragmatic weakness and that oxidative stress is an upstream activator of nuclear factor-κB. Finally, our results suggest that prevention of mechanical ventilation-induced oxidative stress in the diaphragm could be a useful clinical strategy to prevent or delay mechanical ventilation-induced diaphragmatic weakness.

Dataset Information

Caspase-3 regulation of diaphragm myonuclear domain during mechanical ventilation-induced atrophy.

Rationale

Objective

Methods

Measurements and main results

Conclusions

Publications

Caspase-3 regulation of diaphragm myonuclear domain during mechanical ventilation-induced atrophy.

Similar Datasets

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