Skeletal Muscle Inflammation, Oxidative Stress and DNA Repair in Age-Related Sarcopenia

For this project, we will continue to gain mechanistic insight into age-related muscle loss
and to maximize the utility of the tissue we previously collected (Claude D. Pepper Older
Americans Independence Center (OAIC); Skeletal muscle apoptosis and physical performance;
Oxidative RNA/DNA damage and repair in aged human muscle (Developmental Study), IRB #
429-2005) and we will collect muscle tissue from additional young subjects. This project will
specifically test whether inflammatory pathways and DNA repair mechanisms are altered and/or
involved in the development of sarcopenia and the related decline in physical function
observed in the elderly.

Aim 1. We will further determine the association of skeletal muscle mass and function with
intramuscular mediators of inflammation. Focus will be on inflammatory proteins (e.g.,TNF,
TNFR1, pIkBα, pIKKb, CCL2, ZIP14, ZnT2) and genes (e.g., IL-6, TNFa, IL11β, IL-8, CCL2, CCR2,
NFkB p50, NFkB p65, ZIP14) and metals (e.g., copper, zinc, and iron). We hypothesize that the
majority of these markers will be upregulated in muscle from older individuals when compared
to young.

Aim 2. For the first time, we will determine the age related effect of DNA damage on pattern
and dynamics of mRNA translation in human muscle tissue by genome wide analysis using
"ribosome profiling." The recently developed deep-sequencing techniques of RNA-seq and
"ribosome profiling" will be implemented on human muscle. This will allow us to explore on a
genomic scale and at single-nucleotide resolution, the effect of age-related DNA damage on
transcriptional fidelity and translational kinetics. Importantly, for the first time, these
phenotype changes will be compared with genome mapping of DNA damage, a major factor driving
mammalian aging. We hypothesize that older muscle has greater modification of translational
patterns compared to young muscle.

Muscle tissue samples remaining following the completion of this research will be stored and
used in the future to explore new avenues of research related to aging.

Inclusion Criteria:

- males and females aged 20-35.

- willing and able to give informed consent.

Exclusion Criteria:

- High physical activity level (i.e., the subject has spent greater than 300 minutes per
week in the past 2 month performing structured physical activity, such as exercising
at a gym and/or weight training)

- Active treatment for cancer or history of cancer in the past 3 years

- Congestive heart failure NYHA Class III or IV

- Previous stroke with upper and/or lower extremities involvement within the last 6
months

- Peripheral vascular disease Fontaine Class III/IV

- History of life-threatening cardiac arrhythmias, stroke, severe Parkinson's disease or
severe neurological disorders likely to interfere with physical function

- Renal disease requiring dialysis

- Lung disease requiring steroids

- Lower extremity amputation

- Complicated diabetes

- Life-threatening illnesses with an estimated life expectancy less than 1 year

- Anticoagulant therapy (aspirin use is allowed, but participants will be asked to stop
taking it 48 hours prior to muscle biopsy)

- Involved in active weight loss > 5 kg in prior 3 months

- Pregnancy (determined by a pregnancy test)

- Lidocaine allergy

Temporary exclusion criteria:

- Recent bacterial infection (< 2 weeks)

- Acute febrile illness in previous 2 months

- High blood pressure (i.e., BP ≥ 160/90 mm Hg) at the visit (subject will be referred
to his/her physician and reevaluated after appropriated therapy being instituted)

- Taking aspirin within 48 hours preceding biopsy

- Performing exercise 48 hours prior to the biopsy.