Potential novel therapies for chronic obstructive pulmonary disease.

While considerable progress has been made in development of drugs for asthma, there have been few advances in the treatment of chronic obstructive pulmonary disease (COPD). New therapeutic approaches to prevent disease progression are urgently needed and these will arise out of better understanding of the disease process at a cell and molecular level. The inflammatory response in COPD differs markedly from that of asthma, with differences in inflammatory cells, mediators and response to therapy. The neutrophilic inflammation is orchestrated by chemotactic factors, such as interleukin (IL)-8, other CXC chemokines and leukotriene B4; receptor blockers (CXCR1, CXCR2, BLT antagonists) or synthesis inhibitors (5'-lipoxygenase inhibitors) might be effective. Tumour necrosis factor (TNF) alpha may be an important amplifying cytokine and there are several strategies for blocking it (antibodies, soluble receptors, TACE inhibitors). IL-10 is effective in blocking the synthesis of IL-8 and TNF alpha as well as proteases. Oxidative stress and peroxynitrite may be important in COPD; more effective antioxidants are now in development. The inflammatory response in COPD is essentially steroid-resistant so that alternative anti-inflammatory treatments are needed. Phosphodiesterase 4 inhibitors look promising in early clinical studies. Nuclear factor-kappa B inhibitors and p38 MAP kinase inhibitors may also be effective. Several protease inhibitors are in development including those for neutrophil elastase, selective matrix metalloproteinase and cathepsin.