Wednesday Afternoon Poster presentations Posters displayed from 1:00–6:00 pm. One-hour author presentation times are staggered from 2:00–3:00 pm., 3:00–4:00 pm., and 4:00–5:00 pm.: B-30 Free Communication/Poster – Skeletal Muscle, Cytokines and Apoptosis: WEDNESDAY, MAY 31, 2006 2:00 PM – 5:00 PM: ROOM: Hall B
Skeletal muscle injury results in the up-regulation of collagen metabolism and remodeling of the extracellular matrix. However, the signals that regulate this complex process are poorly understood. In vivo, TNF-? blockade significantly decreased the expression of type I collagen mRNA in dystrophic muscle.
PURPOSE: To determine whether TNF-? stimulates collagen metabolism in cultured C2C12 myoblasts and differentiated myotubes as well as in cultured fibroblasts.
METHODS: Cultured C2C12 myoblasts and differentiated myotubes and skeletal muscle fibroblasts were exposed to TNF-? at concentrations of 3-, 6-, or 9 ng/ml for 24-, 48-, or 72 hours (n = 6/group). Cells were harvested and total RNA was isolated. Realtime quantitative PCR was used to measure the expression of type I collagen mRNA.
RESULTS: Irrespective of dose or time, TNF-? significantly (P <0.05) down-regulated the expression of type I collagen mRNA in the myoblasts and myotubes. In contrast, TNF had no impact on type I collagen mRNA in cultured fibroblasts.
CONCLUSION: Our results highlight the complexity of collagen metabolism regulation in an intact organism and suggest that TNF-? likely stimulates collagen metabolism in damaged muscle indirectly by mediating the behavior of inflammatory cells such as macrophages. This work was supported by the Muscular Dystrophy Association.