Background: Hemolysis causes anemia in falciparum malaria, but its contribution to microvascular pathology in severe malaria (SM) is not well characterized. In other hemolytic diseases, release of cell-free hemoglobin causes nitric oxide (NO) quenching, endothelial activation, and vascular complications. We examined the relationship of plasma hemoglobin and myoglobin to endothelial dysfunction and disease severity in malaria. Methods: Cell-free hemoglobin (a potent NO quencher), reactive hyperemia peripheral arterial tonometry (RH-PAT) (a measure of endothelial NO bioavailability), and measures of perfusion and endothelial activation were quantified in adults with moderately severe ( ) np78 or severe (np49) malaria and control subjects (np16) from Papua, Indonesia. Results: Cell-free hemoglobin concentrations in patients with SM (median, 5.4 ?mol/L; interquartile range [IQR], 3.2-7.4 ?mol/L) were significantly higher than in those with moderately severe malaria (2.6 ?mol/L; IQR, 1.3-4.5 ?mol/L) or controls (1.2 ?mol/L; IQR, 0.9-2.4 ?mol/L; P <.001). Multivariable regression analysis revealed that cell-free hemoglobin remained inversely associated with RH-PAT, and in patients with SM, there was a significant longitudinal association between improvement in RH-PAT index and decreasing levels of cell-free hemoglobin (Pp.047). Cell-free hemoglobin levels were also independently associated with lactate, endothelial activation, and proinflammatory cytokinemia. Conclusions: Hemolysis in falciparum malaria results in NO quenching by cell-free hemoglobin, and may exacerbate endothelial dysfunction, adhesion receptor expression and impaired tissue perfusion. Treatments that increase NO bioavailability may have potential as adjunctive therapies in SM. � 2009 by the Infectious Diseases Society of America. All rights reserved.
|Number of pages||8|
|Journal||Journal of Infectious Diseases|
|Publication status||Published - 2009|