Activated lymphocytes secretome inhibits differentiation and induces proliferation of C2C12 myoblasts.
OBJECTIVE
ageing is associated with a marked decline in immune function which may contribute to the local environment that can influence the regenerative process of skeletal muscle cells.


METHODS
Herein, we focused on determining the effect of an activated immune system secretome on myoblast differentiation and proliferation as possible means to attenuate adverse effects of muscle aging. C2C12 myoblasts were used as model to assess the impact of lymphocyte conditioned media (CM) following anti-CD3/IL-2 activation.


RESULTS
Myoblasts cultured with activated lymphocytes CM exhibited reduced morphological and biochemical differentiation (98±20, p<0.005) and increased entry to the S Phase of the cell cycle (61%±7, p<0.001), when compared with myoblasts cultured with non-activated lymphocytes CM. Associated with increased proliferation and reduced differentiation, muscle specific transcription factors MyoD and myogenin were significantly reduced in C2C12 treated with activated lymphocytes CM vs control CM, respectively (myoD: 0.5±0.12 fold reduction P<0.005); myogenin: 0.38±0.08 fold reduction; p<0.005). Moreover, key protein of proliferation pERK1/2 increased (46±11U/ml, p<0.05) whereas mediator of differentiation pAkt decreased (21±12U/ml, p<0.05) in C2C12 treated with activated vs. non-activated CM.


CONCLUSIONS
our data demonstrate that, following activation, secretome of the immune system cells elicit marked regulatory effects on skeletal muscle growth and differentiation; enhancing the former with the loss of the latter.
Work was performed in: Institute for Biomedical Research into Human Movement and Health (IRM), Manchester, Manchester, UK.
Nasser
N
Al-Shanti
Peter
P
Durcan
Sarah
S
Al-Dabbagh
Georgi A
GA
Dimchev
Claire E
CE
Stewart
D000328:Adult; D000818:Animals; D002453:Cell Cycle; D002454:Cell Differentiation; D002460:Cell Line; D049109:Cell Proliferation; D048430:Cell Shape; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D051379:Mice; D017570:MyoD Protein / Q000235:genetics / Q000378:metabolism; D032446:Myoblasts / Q000166:cytology* / Q000378:metabolism; D018008:Myogenin / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D055815:Young Adult
D017570:MyoD Protein; D018008:Myogenin; D012333:RNA, Messenger; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases