P102: PLASMA FREE HEMOGLOBIN AND REACTIVE OXYGEN SPECIES IN SICKLE CELL ANAEMIA PATIENTS UNDER HYDROXYUREA AND GLUTAMINE THERAPY
Authors: A Giannaki, S Fortis, H Georgatzakou, A Xidaki, M Liosi, C Fountzoula, E Papageorgiou, M Antonelou, S Delicou, A Kriebardis
Journal: HemaSphere (2022)

Background: Sickle Cell Anemia (SCA), a quite common hemoglobinopathy in Greece, is a consequence of abnormal hemoglobin S production (HbS). When the oxygen tension is low, HbS polymerization occurs, resulting in red blood cells (RBC) sickling that affects membrane integrity, cell deformability and rheological behavior. Thus, SCA provokes reduced RBCs survival, chronic hemolytic anemia, oxidative stress and microvascular occlusion. Currently, RBC transfusion and hydroxyurea supplementation are the major disease-modifying therapies available for SCD. In addition, L-glutamine oral therapy has been proposed as an anti-oxidative agent for SCA. Aims: The purpose of this study is to measure the oxidative status of RBCs and hemolysis in SCA patients under simultaneous hydroxyurea and L-glutamine therapy. Methods: Eighteen SCA patients (52±12 years old, HbS=68,02±9.40%, on average) as well as sixteen similar age-and gender-matched healthy volunteers (controls) participated in the present study. Six patients were under no therapy before glutamine intake, eight patients were under single hydroxyurea therapy and four patients were under blood transfusion therapy. After signing an informed consent, patients took a dose range of 10-30g glutamine (Glutamine DB EXTRA supplement) daily for a 4-month period. Blood sampling were taken before glutamine intake and during a period of 2–4 months after it. Intracellular RBC Reactive Oxygen Species (iROS) were measured by Flow Cytometry. Osmotic Fragility test (mean corpuscular fragility, MCF) and plasma free hemoglobin (p-F-Hb) were also determined. Statistical analysis was performed by GraphPad Prism 8.0.3 and SPSS v.27 software. Results: All patients had significantly increased iROS levels (632,30±44,83 AU) compared to controls (443.07±69.40 AU, p<0.01), while these under transfusion therapy had only slightly increased values (506.50±31.80 AU, p<0,05). The group of hydroxyurea treatment had lower iROS levels (584.00±87.00 AU) compared to the no therapy group (614.34±23.56 AU, p<0.05). Co-administration of hydroxyurea and glutamine resulted in a 22% decrease in iROS within a two-month period, which was preserved until the end of the four-month period. All patients had decreased RBC MCF (MCF=0.337±0.040% NaCl) compared to controls (MCF=0.46±0.01% NaCl), a finding that was unaffected by hydroxyurea intake (MCF=0.338±0.044% NaCl), a two (MCF=0,331±0,054% NaCl) and four-month (MCF=0.337±0.047% NaCl) glutamine intake period and transfusion therapy (MCF=0.326±0.031% NaCl) (p<0.01). Total bilirubin (T-BIL) was increased in the no therapy group (2.46mgr/dl±0.28) compared to controls (0.63mgr/dl±0.17), while p-F-Hb was increased in all patients (24.34mgr/dl±11.98 vs controls 7.12mgr/dl±2.90) (p<0.01). Patients under hydroxyurea treatment showed a 19.02% decrease in T-BIL levels but not significant different p-F-Hb levels. Finally, concomitant hydroxyurea and glutamine administration seemed to cause a further decrease in T-BIL and p-F-Hb levels (T-BIL;23.24%, p-F-Hb;65.38% after a two-month period intake). Summary-Conclusion: RBCs of patients under simultaneous hydroxyurea and glutamine supplementation scheme cope better with oxidative and hemolysis stresses. L-glutamine seems to be a candidate antioxidant supplement able to deal with basic symptoms of SCA. References 1. Ogu et al, Am J Hematol 2021; 96(1) E38-E40 2. Zaidi et al, Contemp Clin Trials 2021; 110