Effects of Low-grade Systemic Inflammation on Muscle Protein Synthesis and Breakdown in the Aged Skeletal Muscle.
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 入组人数
- 44
- 试验地点
- 2
- 主要终点
- Change in protein expression level of proteasome subunits
研究概览
简要总结
The development of a low-grade, chronic, systemic inflammation observed in the elderly (inflammaing) has been associated with increased risk for skeletal muscle wasting, strength loss and functional impairments. According to studies performed in animals and cell cultures increased concentrations of pro-inflammatory cytokines such as IL-6 and TNF-α as well as increased levels of hs-CRP lead to elevated protein degradation through proteasome activation and reduced muscle protein synthesis (MPS) via downregulation of the Akt-mTOR signaling pathway. However, evidence regarding the effects of inflammaging on skeletal muscle mass in humans is lacking. Thus, the present study will compare proteasome activation and the protein synthetic response in the fasted and postprandial period between older adults with increased systemic inflammation and their healthy control counterparts.
详细描述
A total number of > 60 male, older adults aged 63-73 years will be initially screened for systemic levels of hs-CRP and IL-6. Of these, 24 individuals that will comply with the study criteria will be allocated to either a High (IL6: ≥ 1.7 pg/ml; hs-CRP: > 1.0 mg/L) (n=12) or a Low (IL6: < 1.7 pg/ml; hs-CRP: < 1.0 mg/L) (n=12) systemic inflammation group. Approximately 2 weeks before the experimental trial, anthropometry, resting metabolic rate (RMR), body composition (with DXA), sarcopenia status, functional capacity and the knee-extension one repetition maximum (1RM) will be assessed in individuals from both groups. In addition, levels of habitual physical activity will be assessed using accelerometry (over a 7-day period) and daily dietary intake will be monitored through 7-day diet recalls in all participants. 1 week before the experimental day an oral glucose tolerance test (OGTT) will be also performed over a 2-hour period, with blood sampling every 15min during the first hour and every 30min during the second hour. The day before the experimental trial, participants will consume 150ml of D2O 70% atom as a bolus. In the experimental day, participants will arrive at the laboratory after an overnight fast and a baseline blood sample and a muscle biopsy from vastus lateralis muscle will be collected. Immediately after, participants will perform 8 sets with 10 repetitions at 80% of 1RM and 2 min rest between each set, on a knee-extension machine. After exercise, they will ingest 0.4 g whey protein isolate/kg body weight as single bolus and then they will remain in a sitting position over a 3-hour period. Blood samples will be collected every 30min during the 3-hour postprandial period while a second muscle biopsy will be obtained at 3h.
研究设计
- 研究类型
- Interventional
- 分配方式
- Non Randomized
- 干预模型
- Parallel
- 主要目的
- Basic Science
- 盲法
- Double (Participant, Investigator)
入排标准
- 年龄范围
- 63 Years 至 75 Years（Adult, Older Adult）
- 性别
- Male
- 接受健康志愿者
- 是
入选标准
- •Non-smokers.
- •BMI ≥18.5 & BMI ≤ 35 kg/m
- •Moderately active but with no regular participation in heavy resistance exercise within the last 6 months.
- •Absence of chronic disease (i.e. cancer, metabolic, cardiac, or neurological diseases).
- •Free and independently living.
排除标准
- •Organ failure (unstable, renal, respiratory, liver).
- •Chronic use of corticosteroid medication.
- •Recent use of antibiotics.
- •Presence of frailty.
- •Body weight variation over the past 6mo > 10% or weight loss of more than 3kg in the last 3 months.
- •Use of anti-inflammatory or lipid-lowering medication (i.e., statins).
- •Use of medication interacting with muscle metabolism.
研究组 & 干预措施
High systemic inflammation
Individuals assigned in the high systemic inflammation group will be characterized by IL6: ≥ 1.7 pg/ml and hs-CRP: > 2.0 mg/L.
干预措施: Instantized Whey Protein Isolate (Dietary Supplement)
Low systemic inflammation
Individuals assigned in the high systemic inflammation group will be characterized by IL6: < 1.7 pg/ml and hs-CRP: < 1.0 mg/L.
干预措施: Instantized Whey Protein Isolate (Dietary Supplement)
结局指标
主要结局
Change in protein expression level of proteasome subunits
时间窗: At baseline and 180 min following protein ingestion.
Immunoblot analysis will be used to detect protein expression levels of proteasome (β5, β2 and β1) and immunoproteasome (β5i, β2i and β1i) subunits.
Change in proteasome activities in muscle
时间窗: At baseline and 180 min following protein ingestion.
Chymotrypsin-like (CT-L), caspase-like (C-L) and trypsin-like (T-L) proteasome activities will be assayed with hydrolysis of the fluorogenic peptide LLVY-AMC, LLE-AMC and LSTR-AMC, respectively.
Change in muscle protein synthesis (MPS)
时间窗: At baseline and 180 min following protein ingestion.
Using deuterium oxide (D2O) 70% atom administration. Individuals will consume a single bolus of 150ml D20 the day before the clinical trial and muscle biopsy samples, collected before and after the exercise bout and protein ingestion, will be analyzed for isotopic measurement using GC-P-IRMS.
Change in intracellular signaling proteins in muscle
时间窗: At baseline and 180 min following protein ingestion.
Phosphorylation levels of Akt, mammalian target of rapamycin (mTOR), p70S6K and ribosomal protein S6 (rpS6) will be measure using western blotting.
Systemic inflammation
时间窗: At baseline.
Levels of systemic inflammation will be assessed by measuring serum levels of hs-CRP, IL-6 and TNF-α.
次要结局
- Total antioxidant capacity(At baseline.)
- Oxidized glutathione in blood(At baseline.)
- Glucose concentration in blood(At baseline and at 30 min, 60 min, 90 min, 120 min, 150 min and 180 min following protein ingestion.)
- Resting metabolic rate (RMR)(At baseline.)
- Reduced glutathione in blood(At baseline.)
- Insulin concentration in blood(At baseline and at 30 min, 60 min, 90 min, 120 min, 150 min and 180 min following protein ingestion.)
- Malondialdehyde in serum(At baseline.)
- Insulin sensitivity(At baseline.)
- Protein carbonyls in serum(At baseline.)
- White blood cell count in blood(At baseline.)
- Functional performance(At baseline)
- Lower limb muscle strength(At baseline)
- Physical activity(Over a 7-day period at baseline.)
- Dietary intake(Over a 7-day period at baseline.)
- Body composition(At baseline)
- Body Mass Index (BMI)(At baseline)
- Skeletal muscle index(At baseline)
- Grip strength(At baseline)
研究者
Ioannis G. Fatouros
Associate Professor
University of Thessaly