HDAC9 and chronic obstructive pulmonary disease: Given that COPD is characterized by relative steroid resistance [5, 42–44] and that IL-8 is a potent chemokine for neutrophil recruitment [45], these observations suggest that re-addressing the histone acetylation/deacetylation imbalance with a potent HDAC activator like theophylline may be effective in restoring glucocorticoid sensitiveness in these patients thus enhancing their therapeutic potential.