Om at kronisk betennelse svekker muskler, spesielt i alderdom. Det er mengden av TNF-a og varigheten som avgjør om det virker muskelsvekkende eller ikke. Store mengder over lang tid tærer på muskelen ved at cellene går inn i apoptose (celledød).
«Thus, the negative effect of systemic inflammation on muscle strength at old age may only become apparent when it exceeds a certain threshold and persists for a prolonged period.»
«Satellite cell function may be affected by circulating factors, as muscle regeneration in old mice sharing the circulation of young mice is not impaired. Chronic low-grade systemic inflammation in old organisms may be that environmental factor.»
«TNFα destabilizes MyoD, a muscle-specific transcription factor involved in satellite cell proliferation and differentiation, and induces apoptosis of satellite cells, particularly at old age. »
«Yet, the increase in TNFα during the normal inflammatory response helps, rather than impairs, the repair process. This apparent contradiction may be resolved by the fact that the effects of TNFα are concentration and time dependent.»