Angiogenesis in chronic lung disease.

Chronic lung diseases like COPD, severe progressive pulmonary hypertension (PH), and interstitial lung diseases all have a lung vascular disease component. Cellular and molecular mechanisms of pulmonary vascular remodeling have been experimentally explored in many animal models, and it is now clear that microvessels are involved. In emphysema patients, there is a loss of lung microvessels, and in many forms of severe PH there is obliteration of precapillary arterioles by angioproliferation. Thus, COPD/emphysema and severe angioproliferative PH are on the opposite ends of a spectrum of vascular biology responses. Animal experiments have provided insight regarding some of the initiating events that shape the various forms of pulmonary vascular remodeling. In pulmonary fibrosis and in the postinjury phase of acute lung injury, the angiogenic/angiostatic balance is also affected. This review will therefore discuss angiogenesis in several chronic lung diseases and will speculate on how altered vascular homeostasis may contribute to lung disease development.