Deregulated Stat3 signaling dissociates pulmonary inflammation from emphysema in gp130 mutant mice

Interleukin (IL)-6 is a potent immunomodulatory cytokine that is associated with emphysema, a major component of chronic obstructive pulmonary disease (COPD). IL-6 signaling via the gp130 coreceptor is coupled to multiple signaling pathways, especially the latent transcription factor signal transducer and activator of transcription (Stat)3. However, the pathological role of endogenous gp130-dependent Stat3 activation in emphysema is ill defined. To elucidate the role of the IL-6/gp130/Stat3 signaling axis in the cellular and molecular pathogenesis of emphysema, we employed a genetic complementation strategy using emphysematous gp130F/F mice displaying hyperactivation of endogenous Stat3 that were interbred with mice to impede Stat3 activity. Resected human lung tissue from patients with COPD and COPD-free individuals was also evaluated by immunohistochemistry. Genetic reduction of Stat3 hyperactivity in gp130F/F:Stat3−/+ mice prevented lung inflammation and excessive protease activity; however, emphysema ...