March 6, 2023

Cell-free hemoglobin in pulmonary hypertension

Cell-free hemoglobin generated by the lungs may be a therapeutic target for treating pulmonary arterial hypertension, Vanderbilt researchers found.

Elevated levels of circulating cell-free hemoglobin, which is released from red blood cells in pathologic conditions, have been observed in patients with pulmonary arterial hypertension (PAH). 

To explore mechanisms for elevated cell-free hemoglobin in PAH, Jamie Meegan, PhD, Evan Brittain, MD, MSCI, and colleagues analyzed cell-free hemoglobin generated by the pulmonary circulation in patients with PAH and healthy controls. 

They found that patients with PAH have increased transpulmonary cell-free hemoglobin that is associated with increased pulmonary vascular resistance and mean pulmonary arterial pressure. Microscopy studies of lung tissue sections showed elevated hemoglobin alpha in areas of occlusion — an environment conducive to red blood cell rupture. The researchers also showed that markers of cell-free hemoglobin clearance were differentially regulated in patients with PAH and especially impaired in patients with hereditary PAH. 

The findings, reported in Pulmonary Circulation, support further studies to determine whether cell-free hemoglobin may be a therapeutic target for treating PAH.

In addition to Meegan and Brittain, VUMC co-authors include Vern Kerchberger, MD, Niki Fortune, Brennan McNeil, Julie Bastarache, MD, Eric Austin, MD, MSCI, Lorraine Ware, MD, and Anna Hemnes, MD. 

The research was supported by the National Institutes of Health (grants HL142720, HL146588, HL158906, HL163960, HL150783, HL094296), Francis Family Foundation, and Gilead Reseach Scholars.