In thalassemia, low bioavailability of the amino acid arginine could be a factor in pulmonary hypertension, the increase of blood pressure in the pulmonary artery, pulmonary vein or pulmonary capillaries, new research found.

Pulmonary hypertension is a frequent issue seen in patients with thalassemia, an inherited blood disorder that results in abnormal formation of hemoglobin, the protein in red blood cells that carries oxygen.

The study assessedd 27 thalassemia patients. It found that hemolysis (rupturing of red blood cells), coagulation abnormalities, and dysregulation of the amino acid arginine were leading factors linked with pulmonary hypertension.

Argninase metabolism is disrupted when the enzyme arginase is released into the bloodstream through rupture of red blood cells, resulting in low bioavailability of the amino acid arginine.

In previous work, the authors had found arginine deficiency to be a major factor in acute pain episodes of sickle cell disease.

A deficiency of nitric oxide, a potent vasodilator, has been identified in sickle cell disease and may contribute to episodes of blocked vessels and pain, and arginine is a building block of nitric oxide.

A phase two clinical trial report in 2013 found that arginine therapy resulted in reduced use of pain medications and hospitalization during acute pain episodes of sickle cell disease.

First author Claudia R. Morris, MD, associate professor of pediatrics and emergency medicine at Emory University School of Medicine and the Emory Children’s Center for Cystic Fibrosis and Airways Disease Research, said:

“We are finding that arginine dysregulation is an important hematologic mechanism beyond sickle cell disease. This new study shows that it plays a role in thalassemia patients as well and may contribute to cardiopulmonary dysfunction. Interventions aimed at restoring arginine bioavailability could be a promising area of focus for new therapeutics."

Journal reference:

Morris, C. R., Kim, H.-Y., Klings, E. S., Wood, J., Porter, J. B., Trachtenberg, F., Sweeters, N., Olivieri, N. F., Kwiatkowski, J. L., Virzi, L., Hassell, K., Taher, A., Neufeld, E. J., Thompson, A. A., Larkin, S., Suh, J. H., Vichinsky, E. P., Kuypers, F. A. and the Thalassemia Clinical Research Network (2015) Dysregulated arginine metabolism and cardiopulmonary dysfunction in patients with thalassaemia British Journal of Haematology, 169: 887–898. doi: 10.1111/bjh.13452

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