Artemisinin derivative-containing therapies and abnormal hemoglobin: Do we need to adapt the treatment?

BACKGROUND: Artemisinin-based treatment in malaria patients with abnormal hemoglobin may be ineffective because of their genetic particularity, which could lead to resistance. The main purpose of this study was to assess the effect of artemisinin derivatives on in vivo parasite clearance according to erythrocyte variants. In vivo response was investigated through retrospective data obtained over a 42-day artemether-lumefantrine/artesunate amodiaquine efficacy protocol conducted from 2012 to 2016. RESULTS: A total of 770 patients in Côte d'Ivoire attending the hospitals of Anonkoua-koute (Abidjan), Petit Paris (Korhogo), Libreville (Man), Dar es salam (Bouaké), Ayamé and Yamoussoukro with acute uncomplicated falciparum malaria were selected for successful hemoglobin typing. HbAS, HbSS, HbAC, and HbSC genotypes were found. Parasite clearance time was obtained for 414 patients. In the population with abnormal hemoglobin, parasite densities on admission and parasite clearance rates were significantly lower in the HbSC group compared to HbAA (p = 0.02 and p = 0.007, respectively). After PCR correction on day 42, the acute treatment rate was 100% for each group. Parasite half-life and time for initial parasitaemia to decline by 50 and 99% were longer for the HbSC group (p < 0.05). The study also investigated the prevalence of K13-propeller polymorphisms across different hemoglobin genotype groups. A total of 185 and 63 samples were sequenced in the HbAA group and patients with abnormal Hb, respectively. Only two nonsynonymous mutations D559N and V510M were found in the HbAA group. CONCLUSION: Although this study proved good efficacy of artemether-lumefantrine and artesunate amodiaquine in the treatment of uncomplicated Plasmodium falciparum malaria in patients with abnormal hemoglobin, the increased delay of parasite clearance may represent a threat to health in these patients in relation with sickle cell crisis, which could support selection of parasites resistant to artemisinin.

TITLE: Thérapies contenant des dérivés de l'artémisinine et hémoglobine anormale : faut-il adapter le traitement ? ABSTRACT: Contexte : Le traitement à base d'artémisinine chez les patients atteints de paludisme et présentant une hémoglobine anormale peut être inefficace en raison de leur particularité génétique, ce qui pourrait entraîner une résistance. L'objectif principal de cette étude était d'évaluer in vivo l'effet des dérivés de l'artémisinine sur la clairance du parasite en fonction des variantes érythrocytaires. La réponse in vivo a été étudiée à travers des données rétrospectives obtenues au cours d'un protocole d'efficacité de 42 jours artéméther-luméfantrine/artésunate-amodiaquine mené dans les années 2012 à 2016. Résultats : Un total de 770 patients en Côte d'Ivoire fréquentant les hôpitaux d'Anonkoua-koute (Abidjan), Petit Paris (Korhogo), Libreville (Man), Dar es salam (Bouaké), Ayamé et Yamoussoukro, présentant un paludisme aigu non compliqué à falciparum ont été sélectionnés pour un typage réussi de l'hémoglobine. Les génotypes HbAS, HbSS, HbAC et HbSC ont été trouvés. Le temps de clairance du parasite a été obtenu pour 414 patients. Dans la population avec une hémoglobine anormale, les densités parasitaires à l'admission et le taux de clairance parasitaire étaient significativement plus faibles dans le groupe HbSC par rapport au groupe HbAA (respectivement, p = 0,02 et p = 0,007). Le RCPA était de 100 % pour chaque groupe après correction par PCR au jour 42. La demi-vie du parasite et le temps nécessaire pour que la parasitémie initiale diminue de 50 et 99 % étaient plus longs pour le groupe HbSC (p < 0,05). L'étude a également examiné la prévalence des polymorphismes du gène K13 dans différents groupes de génotype d'hémoglobine. Un total de 185 et 63 échantillons ont été séquencés respectivement dans le groupe HbAA et chez les patients présentant une Hb anormale. Seules deux mutations non synonymes D559N et V510M ont été trouvées dans le groupe HbAA. Conclusion : Bien que cette étude ait prouvé la bonne efficacité de l'artéméther-luméfantrine et de l'artésunate amodiaquine dans le traitement du paludisme simple à Plasmodium falciparum chez les patients présentant une hémoglobine anormale, le retard accru de clairance parasitaire peut représenter une menace pour la santé de ces patients en relation avec la crise drépanocytaire, et peut favoriser la sélection de parasites résistants à l'artémisinine.

Resuscitation with recombinant hemoglobin rHb2.0 in a rodent model of hemorrhagic shock.

BACKGROUND: Hemoglobin solutions combine volume effect, oxygen-carrying capacity, and vasoactive properties, the latter facilitating restoration of global hemodynamics but endangering microvascular resuscitation. Hemoglobin-evoked vasoconstriction probably is due to nitric oxide scavenging, which can be reduced by genetic modifications of the heme pocket. This study compares resuscitation with a nonhemoglobin colloid and two recombinant hemoglobin solutions with wild-type and reduced nitric oxide-scavenging capacity. METHODS: Twenty-seven awake Syrian golden hamsters fitted with dorsal skinfold chambers underwent a 30 min-hemorrhagic shock (mean arterial pressure [MAP] 30-35 mmHg) and resuscitation with shed blood volume of either 6% dextran 60 (Biophausia, Uppsala, Sweden), recombinant hemoglobin 1.1 (rHb1.1; wild-type nitric oxide-scavenging capacity; 10 g/dl), or recombinant hemoglobin 2.0 (rHb2.0; reduced nitric oxide-scavenging capacity; 10 g/dl; both Baxter Healthcare, Boulder, CO). Macrohemodynamic and laboratory parameters were assessed; microvascular parameters in the skinfold chamber were analyzed by intravital microscopy. RESULTS: Hemorrhagic shock reduced functional capillary density (FCD) by 70% and caused significant metabolic acidosis. Colloid resuscitation led to incomplete recovery of MAP and FCD. Infusion of rHb1.1 completely restored MAP but not FCD, with the smallest arteriolar diameters found in this group. FCD was restored best by resuscitation with rHb2.0, although MAP was lower than in rHb1.1-treated animals. Metabolic acidosis was resolved by both hemoglobin solutions, but not by dextran. CONCLUSION: After resuscitation with rHb1.1, arteriolar vasoconstriction quickly restored MAP, but this was achieved at the expense of FCD. In contrast, after resuscitation with rHb2.0, the recovery of MAP could be translated into a significantly improved FCD.

Effects of recombinant-hemoglobin solutions rHb2.0 and rHb1.1 on blood pressure, intestinal blood flow, and gut oxygenation in a rat model of hemorrhagic shock.

The vasoconstriction induced by hemoglobin-based oxygen carriers (HBOCs), mainly a result of nitric oxide (NO) scavenging, until now has limited the application of HBOCs as resuscitation fluids. In this study, we tested the hypothesis that the new modified recombinant-hemoglobin solution rHb2.0, with a 20 to 30 times lesser NO-scavenging rate, would minimize vasoconstriction without adverse effects on microvascular oxygenation. Responses were compared with those to rHb1.1, a recombinant-hemoglobin solution with a wild-type NO-scavenging rate, as well as an oncotically matched albumin solution. In a fixed-pressure (40 mm Hg) rat model of hemorrhagic shock and resuscitation, rHb2.0 and albumin both restored mean arterial pressure (MAP) to baseline values, whereas rHb1.1 increased MAP to 27% above the baseline value. Mesenteric vascular resistance after resuscitation with rHb2.0 was 57% less than that with rHb1.1. rHb2.0 was found to have 55% greater intestinal oxygen delivery (Do2int ) and resulted in a 27% lower oxygen-extraction rate than did rHb1.1 after resuscitation. Intestinal microvascular Po2 , determined on the basis of oxygen-dependent quenching of palladium-porphyrin phosphorescence, revealed no difference between rHb2.0 and rHb1.1. The findings of this study confirm that the well-known pressure effect of HBOCs is caused by their effect on the NO-scavenging rate; recombinant modification of this rate did not increase MAP during resuscitation compared with baseline values. Although systemic vasoconstriction was absent, intestinal vasoconstriction almost negligible, and Do2int greater after resuscitation with rHb2.0, the effect of rHb2.0 on pH, base-excess and microvascular Po2 levels after resuscitation were comparable to those achieved with the use of the albumin solution.

Resuscitation after hemorrhage using recombinant human hemoglobin (rHb1.1) in rats: effects on nitric oxide and prostanoid systems.

OBJECTIVES: Hemoglobin-based oxygen carriers are designed to replace blood volume and to increase oxygen delivery to tissues after blood loss. The goals of the present study were two-fold: a) to determine the systemic and regional vascular effects of resuscitation with recombinant human hemoglobin (rHb1.1) in rats during controlled hemorrhage; and b) to determine whether nitric oxide (NO) or prostaglandins were involved in the observed responses. DESIGN: Paralyzed, ventilated rats were hemorrhaged (18 mL blood/kg body weight) during halothane anesthesia and allowed to stabilize for 30 mins. Systemic and regional hemodynamics and oxygen delivery were monitored at three time points, using the radioactive microsphere method. Microspheres were first infused at the end of the hemorrhage stabilization period (t=0 min). rHb1.1 (1 g/kg body weight) or rHb1.1 diluent (phosphate buffered saline, 36 mL/kg body weight) were infused over 20 mins and microspheres were administered again, 30 mins later (t=50 mins). Saline (0.5 mL), indomethacin (5 mg/kg to inhibit cyclooxygenase), or NG-monomethyl-L-arginine (L-NMMA, 100 mg/kg, to inhibit NO synthase) were then infused in rHb1.1-treated rats and microspheres injected once more (t=80 mins). SETTING: Research laboratory. SUBJECTS: Male Wistar rats (n=37). INTERVENTIONS: Recombinant human hemoglobin (rHb1.1), rHb1.1 diluent (phosphate buffered saline) resuscitation of hemorrhaged rats. Saline, L-NMMA, or indomethacin treatment after resuscitation. MEASUREMENTS AND MAIN RESULTS: Resuscitation with rHb1.1 increased mean arterial pressure (MAP), cardiac output, and systemic oxygen delivery significantly when compared with diluent. After rHb1.1 resuscitation, regional blood flows were significantly increased in skin, kidney, spleen, and heart compared with diluent resuscitation. Compared with saline treatment after rHb1.1 resuscitation, L-NMMA increased MAP and regional resistances in virtually all tissues; indomethacin did not alter MAP, but increased resistance in the brain. CONCLUSIONS: These data indicate that rHb1.1 resuscitation was more effective than diluent in improving systemic and regional hemodynamics and oxygen delivery, suggesting that rHb1.1 may be of benefit in the treatment of acute blood loss. Increased resistance after L-NMMA in the presence of rHb1.1 indicated that rHb1.1 resuscitation did not eliminate NO dependent circulatory control. Increased resistance after indomethacin in brain indicated that vasodilator prostanoids were important in regulating vascular resistance in these tissues after rHb1.1 resuscitation.