IL6 and chronic obstructive pulmonary disease: The dominance of immunoreactive cells in the COPD-affected airway epithelium over other tissue compartments highlights the essentials of epithelium in inflammatory and defence signalling with more pronounced findings of IL-1α, IL-4, IL-6, IL-7, IL-8, IL-10, MMP-2, TIMP-2, TGF-β1, hBD-3.