These data suggest that S100A8 may not be as strong biomarker as S100A9. Furthermore, it should be reminded that the S100 proteins do not possess any signal peptide that allows them to be secreted by the classical pathway of the endoplasmic reticulum and the golgi apparatus. In relation to our observations, different stimuli may promote a significant release of S100A8/A9 as lipopolysaccharide, granulocyte-macrophage colony-stimulating factor, interleukin-1 beta, whereas other stimuli such as pokeweed mitogen do not induce release of S100A8. This discordant result between PBMC and sera can be also alternatively attributed to the small sampling for PBMC analysis. Even though S100A9 protein has a less significant over-expression in responder sera than in PBMC, it was possible to determine a concentration threshold able to identify non-responders with appropriate sensitivity and specificity. Interestingly, a threshold related to a systematic non-response to the MTX/ETA combination was highlighted in the cohort. This information is of particular interest for clinicians since this combination will not be prescribed to patients exhibiting serum S100A9 concentrations above this cut-off. However, using this threshold, the sensitivity is reduced to 50%. In the literature, two reports attempted to identify predictive biomarkers of response to ETA. However, none of them highlighted a possible interest for S100 proteins. Noteworthy, the work of Fabre et al. showed that elevated serum level of monocyte chemo-attractant protein-1 predicts a good response to ETA treatment. MCP-1 regulates the migration and infiltration of monocytes, CD4 memory T lymphocytes and NK cells. Interestingly, S100 proteins were also related to cell migration via the remodelling of the AB1010 msds cytoskeleton. Thus, these two proteins, namely S100A9 and MCP-1, involved in monocyte migration may be key actors of the response to the soluble form of the TNF-alpha receptor. Duchenne Muscular Dystrophy is a fatal neuromuscular disease characterised by progressive fibre necrosis secondary to the absence of the protein dystrophin from the sarcolemma. This leads to severe muscle wasting and weakness, and eventually death in all patients afflicted with the disease, usually by the third decade of life. A prominent yet commonly ignored feature of DMD is compromised bioenergetical status. A 50% deficit in resting ATP levels in dystrophic skeletal muscle has been reported which is likely reflective of both an increased demand for calcium buffering, satellite cell cycling and muscle regeneration, alongside an inability of cellular energy systems to match this heightened demand with sufficient ATP production. Indeed, functional aberrations in key intracellular energy systems, including the mitochondria, have been consistently reported in the literature. It is likely that these aberrations are strongly associated with the drastically increased intracellular that is observed in dystrophin-deficient myofibres, and contribute significantly to the muscle wasting phenotype of DMD.