The long-term goal of this project is to identify therapies that will preserve diaphragm function in chronic inflammatory conditions including heart failure and chronic obstructive pulmonary disease. Our current focus is loss of specific force in diaphragm which promotes exercise intolerance, breathlessness, and respiratory failure. A promising therapeutic target is tumor necrosis factor (TNF). TNF serum levels are elevated in chronic disease, correlate with muscle weakness, and are a predictor of morbidity and mortality. TNF depresses contractile function of diaphragm and stimulates oxidant production by diaphragm muscle fibers. The oxidants appear to cause weakness since interventions that limit oxidant activity prevent loss of force. Our central hypothesis is that respiratory muscle function can be preserved in chronic inflammatory disease by inhibiting TNF receptor-mediated effects on diaphragm muscle fibers. This project will define signaling events and redox mechanisms by which TNF depresses force and will evaluate pharmacologic and genetic interventions to preserve diaphragm function. We also will evaluate pathophysiologic relevance, defining the role of TNF in a mouse model of disease and testing the capacity of clinical therapeutic agents to preserve diaphragm function. The project addresses three specific aims:
Aim 1. To evaluate sphingolipid signaling as an early post-receptor mechanism by which TNF/TNFR1 stimulates oxidant activity and weakness. Cell culture studies will assess sphingomyelinase activation and ceramide-sensitive signaling events downstream of the TNF receptor subtype 1.
Aim 2. To assess the source, composition, and post-translational target of oxidants that mediate TNF-stimulated weakness. Diaphragm fiber bundles and isolated mitochondria will be used to define ROS and NO contributions via redox assays and pharmacologic and genetic tools.
Aim 3. To test TNF signaling as a contributor to respiratory muscle weakness in heart failure and a potential target for therapy. An animal model of heart failure will be used to define the diaphragm response to chronic inflammation, to test TNF as a systemic mediator, and to evaluate potential therapies that are approved for use in humans.

Public Health Relevance

Chronic inflammatory diseases, including heart failure and emphysema, weaken the muscles used for breathing. This promotes the debilitating sensation of breathlessness, decreases exercise tolerance, and can lead to respiratory failure. The goal of this project is to identify new therapies that preserve respiratory muscle function in order to lessen illness and prolong life.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR055974-04
Application #
8270641
Study Section
Skeletal Muscle and Exercise Physiology Study Section (SMEP)
Program Officer
Nuckolls, Glen H
Project Start
2009-04-01
Project End
2014-02-28
Budget Start
2012-03-01
Budget End
2013-02-28
Support Year
4
Fiscal Year
2012
Total Cost
$279,446
Indirect Cost
$91,267
Name
University of Kentucky
Department
Physiology
Type
Schools of Medicine
DUNS #
939017877
City
Lexington
State
KY
Country
United States
Zip Code
40506
Moylan, Jennifer S; Smith, Jeffrey D; Wolf Horrell, Erin M et al. (2014) Neutral sphingomyelinase-3 mediates TNF-stimulated oxidant activity in skeletal muscle. Redox Biol 2:910-20
Sieck, Gary C; Ferreira, Leonardo F; Reid, Michael B et al. (2013) Mechanical properties of respiratory muscles. Compr Physiol 3:1553-67
Stasko, Shawn A; Hardin, Brian J; Smith, Jeffrey D et al. (2013) TNF signals via neuronal-type nitric oxide synthase and reactive oxygen species to depress specific force of skeletal muscle. J Appl Physiol (1985) 114:1629-36
Ferreira, Leonardo F; Moylan, Jennifer S; Stasko, Shawn et al. (2012) Sphingomyelinase depresses force and calcium sensitivity of the contractile apparatus in mouse diaphragm muscle fibers. J Appl Physiol 112:1538-45
Thornton, Angela M; Zhao, Xiaoli; Weisleder, Noah et al. (2011) Store-operated Ca(2+) entry (SOCE) contributes to normal skeletal muscle contractility in young but not in aged skeletal muscle. Aging (Albany NY) 3:621-34
Ferreira, Leonardo F; Campbell, Kenneth S; Reid, Michael B (2011) Effectiveness of sulfur-containing antioxidants in delaying skeletal muscle fatigue. Med Sci Sports Exerc 43:1025-31
Smith, Jeffrey D; Moylan, Jennifer S; Hardin, Brian J et al. (2011) Prion protein expression and functional importance in skeletal muscle. Antioxid Redox Signal 15:2465-75
Gilliam, Laura A A; Moylan, Jennifer S; Ann Callahan, Leigh et al. (2011) Doxorubicin causes diaphragm weakness in murine models of cancer chemotherapy. Muscle Nerve 43:94-102
Nikolova-Karakashian, Mariana N; Reid, Michael B (2011) Sphingolipid metabolism, oxidant signaling, and contractile function of skeletal muscle. Antioxid Redox Signal 15:2501-17
Ferreira, Leonardo F; Moylan, Jennifer S; Gilliam, Laura A A et al. (2010) Sphingomyelinase stimulates oxidant signaling to weaken skeletal muscle and promote fatigue. Am J Physiol Cell Physiol 299:C552-60

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