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.
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.
|Powers, Scott K; Lynch, Gordon S; Murphy, Kate T et al. (2016) Disease-Induced Skeletal Muscle Atrophy and Fatigue. Med Sci Sports Exerc 48:2307-2319|
|McLean, Julie B; Moylan, Jennifer S; Horrell, Erin M W et al. (2015) Proteomic analysis of media from lung cancer cells reveals role of 14-3-3 proteins in cachexia. Front Physiol 6:136|
|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|
|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|
|Sieck, Gary C; Ferreira, Leonardo F; Reid, Michael B et al. (2013) Mechanical properties of respiratory muscles. Compr Physiol 3:1553-67|
|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|
|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|
|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|
|Ferreira, Leonardo F; Campbell, Kenneth S; Reid, Michael B (2011) N-acetylcysteine in handgrip exercise: plasma thiols and adverse reactions. Int J Sport Nutr Exerc Metab 21:146-54|
Showing the most recent 10 out of 14 publications