Nitrite decreases sickle hemoglobin polymerization in vitro independently of methemoglobin formation

Published by Elsevier Inc..

The root cause of sickle cell disease (SCD) is the polymerization of sickle hemoglobin (HbS) leading to sickling of red blood cells (RBC). Earlier studies showed that in patients with SCD, high-dose nitrite inhibited sickling, an effect originally attributed to HbS oxidation to methemoglobin-S even though the anti-sickling effect did not correlate with methemoglobin-S levels. Here, we examined the effects of nitrite on HbS polymerization and on methemoglobin formation in a SCD mouse model. In vitro, at concentrations higher than physiologic (>1 μM), nitrite increased the delay time for polymerization of deoxygenated HbS independently of methemoglobin-S formation, which only occurred at much higher concentrations (>300 μM). In vitro, higher nitrite concentrations oxidized 100% of normal hemoglobin A (HbA), but only 70% of HbS. Dimethyl adipimidate, an anti-polymerization agent, increased the fraction of HbS oxidized by nitrite to 82%, suggesting that polymerized HbS partially contributed to the oxidation-resistant fraction of HbS. At low concentrations (10 μM-1 mM), nitrite did not increase the formation of reactive oxygen species but at high concentrations (10 mM) it decreased sickle RBC viability. In SCD mice, 4-week administration of nitrite yielded no significant changes in methemoglobin or nitrite levels in plasma and RBC, however, it further increased leukocytosis. Overall, these data suggest that nitrite at supra-physiologic concentrations has anti-polymerization properties in vitro and that leukocytosis is a potential nitrite toxicity in vivo. Therefore, to determine whether the anti-polymerization effect of nitrite observed in vitro underlies the decreases in sickling observed in patients with SCD, administration of higher nitrite doses is required.

Medienart:

E-Artikel

Erscheinungsjahr:

2023

Erschienen:

2023

Enthalten in:

Zur Gesamtaufnahme - volume:473

Enthalten in:

Toxicology and applied pharmacology - 473(2023) vom: 15. Aug., Seite 116606

Sprache:

Englisch

Beteiligte Personen:

Almeida, Luis E F [VerfasserIn]
Smith, Meghann L [VerfasserIn]
Kamimura, Sayuri [VerfasserIn]
Vogel, Sebastian [VerfasserIn]
de Souza Batista, Celia M [VerfasserIn]
Quezado, Zenaide M N [VerfasserIn]

Links:

Volltext

Themen:

9008-37-1
Dimethyl adipimidate
Hemin
Hemoglobin, Sickle
Journal Article
Methemoglobin
Nitrate
Nitrite
Nitrites
Polymerization
Sickle

Anmerkungen:

Date Completed 10.07.2023

Date Revised 23.02.2024

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1016/j.taap.2023.116606

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM35837832X