Supplementation-induced change in muscle carnosine is paralleled by changes in muscle metabolism, protein glycation and reactive carbonyl species sequestering.

Carnosine is a performance-enhancing food supplement with a potential to modulate muscle energy metabolism and toxic metabolites disposal. In this study we explored interrelations between carnosine supplementation (2 g/day, 12 weeks) induced effects on carnosine muscle loading and parallel changes in (i) muscle energy metabolism, (ii) serum albumin glycation and (iii) reactive carbonyl species sequestering in twelve (M/F=10/2) sedentary, overweight-to-obese (BMI: 30.0+/-2.7 kg/m2) adults (40.1+/-6.2 years). Muscle carnosine concentration (Proton Magnetic Resonance Spectroscopy; 1H-MRS), dynamics of muscle energy metabolism (Phosphorus Magnetic Resonance Spectroscopy; 31P-MRS), body composition (Magnetic Resonance Imaging; MRI), resting energy expenditure (indirect calorimetry), glucose tolerance (oGTT), habitual physical activity (accelerometers), serum carnosine and carnosinase-1 content/activity (ELISA), albumin glycation, urinary carnosine and carnosine-propanal concentration (mass spectrometry) were measured. Supplementation-induced increase in muscle carnosine was paralleled by improved dynamics of muscle post-exercise phosphocreatine recovery, decreased serum albumin glycation and enhanced urinary carnosine-propanal excretion (all p<0.05). Magnitude of supplementation-induced muscle carnosine accumulation was higher in individuals with lower baseline muscle carnosine, who had lower BMI, higher physical activity level, lower resting intramuscular pH, but similar muscle mass and dietary protein preference. Level of supplementation-induced increase in muscle carnosine correlated with reduction of protein glycation, increase in reactive carbonyl species sequestering, and acceleration of muscle post-exercise phosphocreatine recovery.

Altered dynamics of lipid metabolism in muscle cells from patients with idiopathic inflammatory myopathy is ameliorated by 6 months of training.

KEY POINTS: Regular exercise improves muscle functional capacity and clinical state of patients with idiopathic inflammatory myopathy (IIM). In our study, we used an in vitro model of human primary muscle cell cultures, derived from IIM patients before and after a 6-month intensive supervised training intervention to assess the impact of disease and exercise on lipid metabolism dynamics. We provide evidence that muscle cells from IIM patients display altered dynamics of lipid metabolism and impaired adaptive response to saturated fatty acid load compared to healthy controls. A 6-month intensive supervised exercise training intervention in patients with IIM mitigated disease effects in their cultured muscle cells, improving or normalizing their capacity to handle lipids. These findings highlight the putative role of intrinsic metabolic defects of skeletal muscle in the pathogenesis of IIM and the positive impact of exercise, maintained in vitro by yet unknown epigenetic mechanisms. ABSTRACT: Exercise improves skeletal muscle function, clinical state and quality of life in patients with idiopathic inflammatory myopathy (IIM). Our aim was to identify disease-related metabolic perturbations and the impact of exercise in skeletal muscle cells of IIM patients. Patients underwent a 6-month intensive supervised training intervention. Muscle function, anthropometric and metabolic parameters were examined and muscle cell cultures were established (m. vastus lateralis; Bergström needle biopsy) before and after training from patients and sedentary age/sex/body mass index-matched controls. [14 C]Palmitate was used to determine fat oxidation and lipid synthesis (thin layer chromatography). Cells were exposed to a chronic (3 days) and acute (3 h) metabolic challenge (the saturated fatty acid palmitate, 100 µm). Reduced oxidative (intermediate metabolites, -49%, P = 0.034) and non-oxidative (diglycerides, -38%, P = 0.013) lipid metabolism was identified in palmitate-treated muscle cells from IIM patients compared to controls. Three days of palmitate exposure elicited distinct regulation of oxidative phosphorylation (OxPHOS) complex IV and complex V/ATP synthase (P = 0.012/0.005) and adipose triglyceride lipase in patients compared to controls (P = 0.045) (immunoblotting). Importantly, 6 months of training in IIM patients improved lipid metabolism (CO2 , P = 0.010; intermediate metabolites, P = 0.041) and activation of AMP kinase (P = 0.007), and nearly normalized palmitate-induced changes in OxPHOS proteins in myotubes from IIM patients, in parallel with improvements of patients' clinical state. Myotubes from IIM patients displayed altered dynamics of lipid metabolism and impaired response to metabolic challenge with saturated fatty acid. Our observations suggest that metabolic defects intrinsic to skeletal muscle could represent non-immune pathomechanisms, which can contribute to muscle weakness in IIM. A 6-month training intervention mitigated disease effects in muscle cells in vitro, indicating the existence of epigenetic regulatory mechanisms.

Effects of running on adiponectin, insulin and cytokines in cerebrospinal fluid in healthy young individuals.

Exercise can prevent the sedentary lifestyle-related risk of metabolic and cognitive decline, but mechanisms and mediators of exercise effects on human brain are relatively unexplored. We measured acute exercise-induced changes in adiponectin, insulin and other bioactive molecules in cerebrospinal fluid (CSF) and serum from young lean individuals. Samples of serum and CSF were obtained before and 1-h after the 90-min run (75-80% HRmax; maximal heart rate), additional serum was taken at finish-line. Body composition, physical fitness, metabolic rate, cognitive functions, food preference, glucose, insulin and albumin were measured. The spectrum of 174 cytokines was assessed by protein arrays, adiponectin was also determined by ELISA and immunoblotting. CSF adiponectin decreased post-exercise by 21.3% (arrays) and 25.8% (ELISA) (p < 0.009). Immunoblotting revealed reduction in a low-molecular-weight-adiponectin (p < 0.005). CSF adiponectin positively correlated with CSF/serum albumin ratio (p < 0.022), an indicator of blood-brain-barrier permeability. CSF and serum adiponectin were positively associated with memory and running-induced changes in insulinemia and CSF insulin. Additionally, running modulated CSF levels of 16 other cytokines. Acute running reduced CSF adiponectin and modulated insulin and albumin in CSF and serum. Associations of adiponectin with memory and metabolism indicate the potential role of this bioactive molecule in mediating exercise-induced adaptive response in human brain.

Effects of hypoxia on adipose tissue expression of NFκB, IκBα, IKKγ and IKAP in patients with chronic obstructive pulmonary disease.

Recently we observed increased adipose tissue (AT) expression of CD40-related signaling proteins but no activation of tumor necrosis factor-α or CD68 in patients with chronic sustained hypoxia resulting from chronic obstructive pulmonary disease (COPD). Transcription factor nuclear factor-κB (NFκB) is involved in cellular responses to hypoxia and activates the proinflammatory gene expression with concomitant upregulation of its own repressors--inhibitors of κB (IκB) in an auto feedback loop. Inhibitor of kappaB kinase (IKK)-γ and inhibitor of kappaB kinase complex-associated protein (IKAP) are further regulatory proteins involved in NFκB signaling. In this study, we hypothesized that chronic sustained hypoxia significantly relates to IκBα, IKKγ and IKAP within the AT in COPD patients. In 20 patients with stable disease, samples of subcutaneous AT were analyzed using real-time PCR. Although no significant differences were observed between two groups categorized by median PaO2 in NFκB (p = 0.065), gene expressions of IκBα, IKKγ and IKAP were all higher in hypoxemic patients (p = 0.033; p = 0.050; p = 0.010, respectively). In multivariate analyses, PaO2 independently predicted AT IκBα, IKKγ and IKAP (R (2) = 0.490, p = 0.012; R (2) = 0.586, p = 0.002; R (2) = 0.504, p = 0.009, respectively). In conclusion, our data suggest significant AT upregulation of IκBα, IKKγ and IKAP by chronic sustained hypoxia in COPD patients.

Circulatory and adipose tissue leptin and adiponectin in relationship to resting energy expenditure in patients with chronic obstructive pulmonary disease.

Increases in resting energy expenditure (REE) likely contribute to weight loss in various chronic diseases. In chronic obstructive pulmonary disease (COPD), relationships between the ventilatory impairment and increased REE, and between disturbances in adipokines and weight loss were previously described. Therefore, we investigated serum levels and adipose tissue expression of leptin and adiponectin, and their relationships to REE in patients with COPD. In 44 patients with stable COPD (38 male; age 62.3+/-7.2 years), REE was assessed using indirect calorimetry. Subcutaneous adipose tissue samples were analyzed using real-time PCR. From underweight [n=9; body mass index (BMI) <20.0 kg.m(-2)], to normal weight-overweight (n=24, BMI=20.0-29.9 kg.m(-2)) and obese patients (n=11; BMI>/=30 kg.m(-2)), REE adjusted for body weight decreased (32.9+/-6.1 vs. 26.2+/-5.8 vs. 23.9+/-6.6 kcal.kg(-1).24 h(-1), p=0.006), serum levels and adipose tissue expression of leptin increased (p<0.001 for both), and serum and adipose tissue adiponectin decreased (p<0.001; p=0.004, respectively). REE was inversely related to serum and adipose tissue leptin (R=-0.547, p<0.001; R=-0.458, p=0.002), and directly to serum adiponectin (R=0.316, p=0.039). Underweight patients had increased REE compared to normal weight-overweight patients, in association with reductions in serum and adipose tissue leptin, and increased serum adiponectin, suggesting a role of adipokines in energy imbalance in COPD-related cachexia.