The respiratory muscles of critically ill patients requiring mechanical ventilation are profoundly weak and infections are a major factor contributing to the development of this debility. The cellular mechanisms by which systemic infection induces respiratory muscle weakness, however, are poorly understood. In other tissues, the effects of infection are mediated by a variety of signaling pathways but virtually nothing is known about the signaling pathways activated in respiratory skeletal muscle in response to infection. The purpose of the experiments in this proposal is to examine this issue. These experiments will test our central hypothesis: p38, JNK, and PKR kinase pathways interact to regulate diaphragm muscle death receptor activation, death receptor active caspase 8 formation, and caspase mediated reductions in diaphragm force generation.
Aim I studies will test the hypothesis that p38 and JNK modulate inflammation induced skeletal muscle caspase 8 activation and contractile dysfunction. Studies will be done using mice given endotoxin and C2C12 muscle cells exposed to cytokines. We will examine the time course of activation of p38 and JNK and will also determine if chemical or genetic inhibition of p38 and/or JNK prevents inflammation induced caspase 8 formation and diaphragm weakness. We will also determine if NADPH oxidase mediated superoxide generation causes skeletal muscle p38 and JNK activation in response to inflammation.
Aim II studies will test the hypothesis that PKR also contributes to inflammation induced skeletal muscle caspase 8 activation and weakness. We will examine the time course of skeletal muscle PKR activation and will determine if chemical or genetic inhibition of PKR prevents inflammation induced skeletal muscle caspase 8 formation and weakness. We will also determine if PACT/RAX activation is responsible for activating PKR in skeletal muscle following inflammatory stimuli.
Aim III studies will test the hypothesis that inflammation induces specific changes in skeletal muscle death receptor complex (DISC) characteristics that are linked to activation of the p38, JNK and PKR signaling pathways. We will both characterize the effects of inflammation on DISC formation, localization, and autocatalytic activity and determine if these alterations can be blocked by inhibition of p38, JNK, and/or PKR signaling pathways. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL081525-04
Application #
7456612
Study Section
Special Emphasis Panel (ZRG1-MOSS-K (07))
Program Officer
Smith, Robert A
Project Start
2006-07-01
Project End
2011-06-30
Budget Start
2008-07-01
Budget End
2009-06-30
Support Year
4
Fiscal Year
2008
Total Cost
$355,629
Indirect Cost
Name
University of Kentucky
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
939017877
City
Lexington
State
KY
Country
United States
Zip Code
40506
Supinski, Gerald S; Alimov, Alexander P; Wang, Lin et al. (2016) Calcium-dependent phospholipase A2 modulates infection-induced diaphragm dysfunction. Am J Physiol Lung Cell Mol Physiol 310:L975-84
Supinski, Gerald S; Alimov, Alexander P; Wang, Lin et al. (2015) Neutral sphingomyelinase 2 is required for cytokine-induced skeletal muscle calpain activation. Am J Physiol Lung Cell Mol Physiol 309:L614-24
Supinski, Gerald S; Callahan, Leigh A (2015) How Important is Diaphragm Function as a Determinant of Outcomes for MICU Patients in Respiratory Failure? Physiology (Bethesda) 30:336-7
Supinski, Gerald S; Wang, Lin; Song, Xiao-Hong et al. (2014) Muscle-specific calpastatin overexpression prevents diaphragm weakness in cecal ligation puncture-induced sepsis. J Appl Physiol (1985) 117:921-9
Callahan, Leigh A; Supinski, Gerald S (2014) Hyperglycemia-induced diaphragm weakness is mediated by oxidative stress. Crit Care 18:R88
Supinski, Gerald S; Callahan, Leigh A (2014) ?-hydroxy-?-methylbutyrate (HMB) prevents sepsis-induced diaphragm dysfunction in mice. Respir Physiol Neurobiol 196:63-8
Callahan, Leigh Ann; Supinski, Gerald S (2013) Prevention and treatment of ICU-acquired weakness: is there a stimulating answer? Crit Care Med 41:2457-8
Supinski, Gerald S; Callahan, Leigh Ann (2010) Calpain activation contributes to endotoxin-induced diaphragmatic dysfunction. Am J Respir Cell Mol Biol 42:80-7
Callahan, Leigh Ann; Supinski, Gerald S (2010) Diaphragm weakness and mechanical ventilation--what's the critical issue? Crit Care 14:187
Supinski, G S; Vanags, J; Callahan, L A (2009) Effect of proteasome inhibitors on endotoxin-induced diaphragm dysfunction. Am J Physiol Lung Cell Mol Physiol 296:L994-L1001

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