Inhaled therapies targeting prostacyclin pathway in pulmonary hypertension due to COPD: systematic review

Pulmonary hypertension in chronic obstructive pulmonary disease: current understanding, knowledge gaps and future directions

PURPOSE OF REVIEW

Despite the advent of effective and mechanistically diverse treatments for pulmonary arterial hypertension (PAH) and their positive impacts on the functional capacities and outcomes for PAH patients, the much larger population of patients with pulmonary hypertension (PH) in chronic lung diseases like chronic obstructive pulmonary disease (PH-COPD) remain without effective therapies.

RECENT FINDINGS

In this review, we will highlight advances in the understanding of PH-COPD pathobiology, the clinical impact comorbid PH has on COPD outcomes, and detail the spectrum of disease and clinical phenotypes that encompass the heterogenous disease manifestations of PH-COPD. Finally, we will examine recent studies exploring the effects of potential treatments for PH-COPD and highlight sub-populations and treatment options that warrant further study.

SUMMARY

As the PAH population-base ages and comorbid diseases become more frequently diagnosed in PAH patients, the need to clearly delineate subpopulations for clinical applications of PH therapies and research becomes even more urgent. Through an improved understanding of the clinical phenotypes of PH-COPD and the overlap with certain subpopulations of PAH, a framework for future research and potential for therapeutic impact is highlighted.

Role of prostanoids, nitric oxide and endothelin pathways in pulmonary hypertension due to COPD

Pulmonary hypertension (PH) due to chronic obstructive pulmonary disease (COPD) is classified as Group 3 PH, with no current proven targeted therapies. Studies suggest that cigarette smoke, the most risk factor for COPD can cause vascular remodelling and eventually PH as a result of dysfunction and proliferation of pulmonary artery smooth muscle cells (PASMCs) and pulmonary artery endothelial cells (PAECs). In addition, hypoxia is a known driver of pulmonary vascular remodelling in COPD, and it is also thought that the presence of hypoxia in patients with COPD may further exaggerate cigarette smoke-induced vascular remodelling; however, the underlying cause is not fully understood. Three main pathways (prostanoids, nitric oxide and endothelin) are currently used as a therapeutic target for the treatment of patients with different groups of PH. However, drugs targeting these three pathways are not approved for patients with COPD-associated PH due to lack of evidence. Thus, this review aims to shed light on the role of impaired prostanoids, nitric oxide and endothelin pathways in cigarette smoke- and hypoxia-induced pulmonary vascular remodelling and also discusses the potential of using these pathways as therapeutic target for patients with PH secondary to COPD.