Effects of 5‐hydroxymethyl‐2‐furfural on the volume and membrane permeability of red blood cells from patients with sickle cell disease

Abstract

Key pointsr We addressed the hypothesis that the heterocyclic aldehyde 5-hydroxymethyl-2-furfural (5HMF) may act synergistically to ameliorate the complications of sickle cell disease through effects on red blood cell (RBC) membrane transport, in addition to its well-known action of increasing the oxygen affinity of the abnormal form of haemoglobin, HbS.r 5HMF was found to reduce deoxygenation-induced dehydration of RBCs, whether in response to maintained deoxygenation or cyclical deoxygenation/re-oxygenation.r Acting at low millimolar concentrations, 5HMF reduced the activity of deoxygenation-induced cation conductance (sometimes termed P sickle ), an effect which correlated with reduction in sickling. 5HMF similarly inhibited deoxygenation-induced activation of the Ca 2+ -activated K + channel (or Gardos channel), an effect not seen following pharmacologically mediated increases in intracellular Ca 2+ via the ionophore A23187. Deoxygenation-induced phosphatidylserine exposure, which is associated with Ca 2+ entry via P sickle , was also inhibited by 5HMF.r By contrast, effects of 5HMF on the K + -Cl − cotransporter (KCC) were modest, with slight inhibition following treatment with N-ethylmaleimide (NEM) to abolish activity of its regulatory protein kinases, but stimulation in RBCs untreated with NEM.r It would therefore appear that an important beneficial action of 5HMF, in addition to effects on HbS oxygen affinity, is reduction in P sickle -mediated Ca 2+ entry following RBC sickling, thereby inhibiting the deleterious sequelae of Gardos channel activation, RBC dehydration and also lipid scrambling. AbstractThe heterocyclic aldehyde 5-hydroxymethyl-2-furfural (5HMF) interacts allosterically with the abnormal form of haemoglobin (Hb), HbS, in red blood cells (RBCs) from patients with sickle cell disease (SCD), thereby increasing oxygen affinity and decreasing HbS polymerization and RBC sickling during hypoxia. We hypothesized that should 5HMF also inhibit the main cation pathways implicated in the dehydration of RBCs from SCD patients -the deoxygenation-induced cation pathway (P sickle ), the Ca 2+ -activated K + channel (the Gardos channel) and the K + -Cl − cotransporter (KCC) -it would have a synergistic effect in protection against sickling, directly through interacting with HbS, and indirectly through maintaining hydration and reducing [HbS]. This study was therefore designed to investigate the effects of 5HMF on RBC volume and K + permeability in vitro. 5HMF markedly reduced the deoxygenation-induced dehydration of RBCs whether in response to maintained deoxygenation or to cyclical deoxygenation/re-oxygenation. 5HMF was found to inhibit P sickle , an effect which correlated with its effects on sickling. Deoxygenation-induced activation of the Gardos channel and exposure of phosphatidylserine were also inhibited, probably indirectly via reduced entry of Ca 2+ through the P sickle pathway. Effects of 5HMF on KCC were more modest with a slight inhibition in N-ethylmaleimide (NEM, 1 mM)-treated RBCs and sti...

The effect of the antisickling compoundGBT1118 on the permeability of red blood cells from patients with sickle cell anemia

“…Similar effects on cation transport and RBC hydration have been observed previously with the heterocyclic aldehyde 5HMF (Hannemann et al. ).…”

2015 Clinical trials update in sickle cell anemia

“…In vitro 5-HMF reduces sickling-induced dehydration (Gardos and P sickle ) while it increases K loss and dehydration mediated by the K-Cl cotransport [83]. A phase 1 clinical trial tested oral doses of AES-103 up to 4,000 mg in 18 patients with SCD, some treated with hydroxyurea, with no significant side effects [84].…”

Orphan drugs for sickle vaso-occlusion: dawn of a new era of targeted treatment

“…119 Reduction in P sickle -mediated Ca 2+ by 5-HMF following erythrocyte sickling has also been observed suggesting that this agent may also have an additional anti-sickling effect by inhibiting the deleterious sequelae of Gardos channel activation. 120 Single doses of 5-HMF were well tolerated in a Phase I study, and showed changes in blood oxygen levels during a hypoxia challenge test consistent with the effects of a left-shifting allosteric hemoglobin modifier. 121 This agent is completing Phase II trials in SCD sponsored by AesRx, LLC, and is expected to enter Phase III trials late in 2015 with sponsorship by Baxter.…”