title: Elevated NF-κB activation is conserved in human myocytes cultured from obese type 2 diabetic patients and attenuated by AMP-activated protein kinase.
abstract: OBJECTIVE
  To examine whether the inflammatory phenotype found in obese and diabetic individuals is preserved in isolated, cultured myocytes and to assess the effectiveness of pharmacological AMP-activated protein kinase (AMPK) activation upon the attenuation of inflammation in these myocytes.
  
  
  METHODS
  Muscle precursor cells were isolated from four age-matched subject groups: 1) nonobese, normal glucose tolerant; 2) obese, normal glucose tolerant; 3) obese, impaired glucose tolerant; and 4) obese, type 2 diabetes (T2D). The level of inflammation (nuclear factor-κB [NF-κB] signaling) and effect of pharmacological AMPK activation was assessed by Western blots, enzyme-linked immunosorbent assay, and radioactive assays (n = 5 for each subject group).
  
  
  RESULTS
  NF-κB-p65 DNA binding activity was significantly elevated in myocytes from obese T2D patients compared with nonobese control subjects. This correlated to a significant increase in tumor necrosis factor-α concentration in cell culture media. In addition, insulin-stimulated glucose uptake was completely suppressed in myocytes from obese impaired glucose tolerant and T2D subjects. It is interesting that activation of AMPK by A769662 attenuated NF-κB-p65 DNA binding activity in obese T2D cells to levels measured in nonobese myocytes; however, this had no effect on insulin sensitivity of the cells.
  
  
  CONCLUSIONS
  This work provides solid evidence that differentiated human muscle precursor cells maintain in vivo phenotypes of inflammation and insulin resistance and that obesity alone may not be sufficient to establish inflammation in these cells. It is important that we demonstrate an anti-inflammatory role for AMPK in these human cells. Despite attenuation of NF-κB activity by AMPK, insulin resistance in obese T2D cells remained, suggesting factors in addition to inflammation may contribute to the insulin resistance phenotype in muscle cells.
authors.affiliation: Centre of Inflammation and Metabolism, Department of Infectious Diseases, Rigshospitalet, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark. cjgreen30@gmail.com
authors.forename: Charlotte J
authors.initials: CJ
authors.lastname: Green
authors.forename: Maria
authors.initials: M
authors.lastname: Pedersen
authors.forename: Bente K
authors.initials: BK
authors.lastname: Pedersen
authors.forename: Camilla
authors.initials: C
authors.lastname: Scheele
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000737:chemistry / Q000378:metabolism*; D015992:Body Mass Index; D002478:Cells, Cultured; D003924:Diabetes Mellitus, Type 2 / Q000276:immunology / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D020536:Enzyme Activators / Q000494:pharmacology; D005260:Female; D018149:Glucose Intolerance / Q000209:etiology; D006801:Humans; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D032342:Muscle Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D032446:Myoblasts / Q000187:drug effects / Q000378:metabolism; D009220:Myositis / Q000517:prevention & control; D016328:NF-kappa B / Q000378:metabolism*; D009765:Obesity / Q000276:immunology / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D052097:Quadriceps Muscle / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D012720:Severity of Illness Index; D051996:Transcription Factor RelA / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D020536:Enzyme Activators; D016328:NF-kappa B; C498143:RELA protein, human; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D055372:AMP-Activated Protein Kinases