A long-term goal of our research for the past 20 years has been to understand mechanisms through which the immune system modulates function and dysfunction of skeletal muscle. In the project for which we request support, we will examine the function of a specific population of immune cells that have the potential to influence sarcopenia, the loss of muscle mass during aging. Currently, there are no treatments for sarcopenia in humans other than exercise and dietary interventions that may not be applicable for the aged. Validation of our model for immune-cell modulation of sarcopenia could provide a gateway to new therapeutic strategies for the slowing of sarcopenia. This outcome would have substantial significance for treating major health problems in the aging human population in which degradation of lifestyle, loss of independent function and development of inactivity-associated diseases can arise from the loss of muscle mass and physical activity in the elderly population. We hypothesize that aging of the immune system contributes to sarcopenia through two processes: 1) reductions in the capacity of bone marrow derived myelomonocytic cells to fuse with skeletal muscle, and 2) shifts in macrophages to a phenotype that promotes muscle wasting. Our experiments that are designed to test this hypothesis will address the following aims:
Aim 1 : Determine the fate of select immune cell populations in aging muscle.
Aim 2 : Determine whether diminishing selected immune cell populations affects sarcopenia or the regenerative capacity of muscle during aging.
Aim 3 : Test whether manipulation of the development of specific immune cell populations can influence sarcopenia. The findings of this investigation will provide the first information concerning the fate of cells of the myelomonocytic lineage in aging muscle and provide new insights into the mechanisms through which cells of that lineage can affect the regenerative capacity of aging muscle. That information can provide the foundation for new therapeutic strategies for addressing sarcopenia, a major health problem in the elderly.

Public Health Relevance

Sarcopenia is the progressive loss of muscle mass that occurs in the elderly that greatly reduces their quality of life and susceptibility to injury. We propose to test whether aging of the immune system reduces the regenerative capacity of aging muscle. Validation of our model for immune-cell modulation of sarcopenia could provide a gateway to new therapeutic strategies for the slowing of sarcopenia.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
5R01AG041147-05
Application #
8897218
Study Section
Skeletal Muscle Biology and Exercise Physiology Study Section (SMEP)
Program Officer
Williams, John
Project Start
2011-09-15
Project End
2017-07-31
Budget Start
2015-08-01
Budget End
2017-07-31
Support Year
5
Fiscal Year
2015
Total Cost
Indirect Cost
Name
University of California Los Angeles
Department
Physiology
Type
Schools of Arts and Sciences
DUNS #
092530369
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
Wehling-Henricks, Michelle; Welc, Steven S; Samengo, Guiseppina et al. (2018) Macrophages escape Klotho gene silencing in the mdx mouse model of Duchenne muscular dystrophy and promote muscle growth and increase satellite cell numbers through a Klotho-mediated pathway. Hum Mol Genet 27:14-29
Wang, Ying; Wehling-Henricks, Michelle; Welc, Steven S et al. (2018) Aging of the immune system causes reductions in muscle stem cell populations, promotes their shift to a fibrogenic phenotype, and modulates sarcopenia. FASEB J :fj201800973R
Tidball, James G (2017) Regulation of muscle growth and regeneration by the immune system. Nat Rev Immunol 17:165-178
Wehling-Henricks, Michelle; Li, Zhenzhi; Lindsey, Catherine et al. (2016) Klotho gene silencing promotes pathology in the mdx mouse model of Duchenne muscular dystrophy. Hum Mol Genet 25:2465-2482
Wang, Ying; Wehling-Henricks, Michelle; Samengo, Giuseppina et al. (2015) Increases of M2a macrophages and fibrosis in aging muscle are influenced by bone marrow aging and negatively regulated by muscle-derived nitric oxide. Aging Cell 14:678-88
Tidball, James G; Wehling-Henricks, Michelle (2014) Nitric oxide synthase deficiency and the pathophysiology of muscular dystrophy. J Physiol 592:4627-38
Tidball, James G; Dorshkind, Kenneth; Wehling-Henricks, Michelle (2014) Shared signaling systems in myeloid cell-mediated muscle regeneration. Development 141:1184-96
Tidball, James G; Bertoni, Carmen (2014) Purloined mechanisms of bacterial immunity can cure muscular dystrophy. Cell Metab 20:927-9
Samengo, Giuseppina; Avik, Anna; Fedor, Brian et al. (2012) Age-related loss of nitric oxide synthase in skeletal muscle causes reductions in calpain S-nitrosylation that increase myofibril degradation and sarcopenia. Aging Cell 11:1036-45
Sakellariou, Giorgos K; Pye, Deborah; Vasilaki, Aphrodite et al. (2011) Role of superoxide-nitric oxide interactions in the accelerated age-related loss of muscle mass in mice lacking Cu,Zn superoxide dismutase. Aging Cell 10:749-60