TNF and chronic obstructive pulmonary disease: But, as previously mentioned for circulating cytokines, the importance of this finding remains somewhat unclear in muscle, since 1) increases in other proinflammatory cytokines were not observed in the skeletal muscle of this patient group, and 2) a similar increase in muscle TNFα was not also observed in the non-AATD COPD patient group who also had evidence of elevated systemic inflammation.