RED BLOOD CELL AQUAPORIN-1 EXPRESSION IS DECREASED IN HEREDITARY SPHEROCYTOSIS

CRISP R; SOLARI L; GARCÍA E; NESSE A; VITTORI D; SCHVARTZMAN G; DONATO H; MALTANERI R; GAMELLA D; RAPETTI MC

ANNALS OF HEMATOLOGY

SPRINGER

Lugar: Berlin; Año: 2016 vol. 95 p. 1595 - 1601

0939-5555

Aquaporin-1(AQP1) is the membrane water channel responsible for changes in erythrocytevolume in response to the tonicity of the medium. Asthe aberrant distribution of proteins in hereditary spherocytosis (HS) generatesdeficiencies of proteins other than those codified by the mutated gene, wepostulated that AQP1 expression might be impaired in spherocytes.AQP1expression was evaluated through flow cytometry in 5 normal controls, 1autoimmune hemolytic anemia, 10 HS (2 mild, 3 moderate, 2 severe, and 3splenectomized), and 3 silent carriers. The effect of AQP1 inhibitors wasevaluated through water flow-based tests: osmotic fragility and hypertoniccryohemolysis. Serum osmolality was measured in 20 normal controls and 13 HS. Theeffect of erythropoietin (Epo) on AQP1 expression was determined in cultures oferythroleukemia UT-7 cells, dependent on Epo to survive.Independentlyof erythrocyte size, HS patients showed a lower content of AQP1 in erythrocytemembranes which correlated with the severity of the disease. In accordance, redblood cells from HS subjects were less sensitive to cryohemolysis than normalerythrocytes after inhibition of the AQP1 water channel. A lower serumosmolality in HS with respect to normal controls suggests alterations duringreticulocyte remodeling. The decreased AQP1 expression could contribute toexplain variable degrees of anemia in hereditary spherocytosis. The finding of AQP1expression induced by Epo in a model of erythroid cells reveals a potentialtreatment that may restore the balance of red cell water fluxes.