The pyruvate kinase activator mitapivat reduces hemolysis and improves anemia in a β-thalassemia mouse model
Alessandro Matte, … , Carlo Brugnara, Lucia De Franceschi
Alessandro Matte, … , Carlo Brugnara, Lucia De Franceschi
Published April 6, 2021
Citation Information: J Clin Invest. 2021;131(10):e144206. https://doi.org/10.1172/JCI144206.
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Research Article Hematology

The pyruvate kinase activator mitapivat reduces hemolysis and improves anemia in a β-thalassemia mouse model

Abstract

Anemia in β-thalassemia is related to ineffective erythropoiesis and reduced red cell survival. Excess free heme and accumulation of unpaired α-globin chains impose substantial oxidative stress on β-thalassemic erythroblasts and erythrocytes, impacting cell metabolism. We hypothesized that increased pyruvate kinase activity induced by mitapivat (AG-348) in the Hbbth3/+ mouse model for β-thalassemia would reduce chronic hemolysis and ineffective erythropoiesis through stimulation of red cell glycolytic metabolism. Oral mitapivat administration ameliorated ineffective erythropoiesis and anemia in Hbbth3/+ mice. Increased ATP, reduced reactive oxygen species production, and reduced markers of mitochondrial dysfunction associated with improved mitochondrial clearance suggested enhanced metabolism following mitapivat administration in β-thalassemia. The amelioration of responsiveness to erythropoietin resulted in reduced soluble erythroferrone, increased liver Hamp expression, and diminished liver iron overload. Mitapivat reduced duodenal Dmt1 expression potentially by activating the pyruvate kinase M2-HIF2α axis, representing a mechanism additional to Hamp in controlling iron absorption and preventing β-thalassemia–related liver iron overload. In ex vivo studies on erythroid precursors from patients with β-thalassemia, mitapivat enhanced erythropoiesis, promoted erythroid maturation, and decreased apoptosis. Overall, pyruvate kinase activation as a treatment modality for β-thalassemia in preclinical model systems had multiple beneficial effects in the erythropoietic compartment and beyond, providing a strong scientific basis for further clinical trials.

Authors

Alessandro Matte, Enrica Federti, Charles Kung, Penelope A. Kosinski, Rohini Narayanaswamy, Roberta Russo, Giorgia Federico, Francesca Carlomagno, Maria Andrea Desbats, Leonardo Salviati, Christophe Leboeuf, Maria Teresa Valenti, Francesco Turrini, Anne Janin, Shaoxia Yu, Elisabetta Beneduce, Sebastien Ronseaux, Iana Iatcenko, Lenny Dang, Tomas Ganz, Chun-Ling Jung, Achille Iolascon, Carlo Brugnara, Lucia De Franceschi

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Figure 2

Mitapivat ameliorated ineffective erythropoiesis in Hbbth3/+ mice.

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Mitapivat ameliorated ineffective erythropoiesis in Hbbth3/+ mice. (A) P...
(A) Plasma EPO in WT and Hbbth3/+ mice. Data are mean ± SD (n = 3). (B) Spleen weight/mouse weight ratio in WT and Hbbth3/+ mice. Mean ± SD (n = 6). (C) Flow cytometry (CD44-Ter119 and cell size markers) of bone marrow and spleen from WT and Hbbth3/+ mice. Mean ± SD (n = 6). (D) Ratio of proerythroblasts plus basophilic erythroblasts/polychromatic plus orthochromatic erythroblasts (maturation index) in spleen and bone marrow from Hbbth3/+ mice by flow cytometry. Mean ± SD (Hbbth3/+, n = 4 vehicle-treated, n = 5 mitapivat-treated; WT, n = 6). (E) ATP content in sorted CD44-Ter119 total erythroblasts from spleen and bone marrow of Hbbth3/+ mice and bone marrow of WT mice. Mean ± SEM (spleen, vehicle-treated, n = 5, versus mitapivat-treated, n = 7; P < 0.05; bone marrow, WT vehicle, n = 4, Hbbth3/+ vehicle-treated, n = 4, versus mitapivat-treated, n = 6; P = NS). (F) ROS levels in erythroblasts from WT or Hbbth3/+ mice. Mean ± SD (WT, n = 4 vehicle-treated and n = 6 mitapivat-treated; Hbbth3/+, n = 6 vehicle and n = 4 mitapivat-treated). (G) Annexin-V+ erythroid cells from WT or Hbbth3/+ mice. Mean ± SD (WT, vehicle-treated n = 6 and mitapivat-treated n = 4; Hbbth3/+, n = 6 each group). (H) mRNA expression of Erfe by qRT-PCR of sorted erythroblasts from bone marrow of WT and Hbbth3/+ mice. Mean ± SD, n = 6. (I) Soluble plasma ERFE levels in WT and Hbbth3/+. Mean ± SD (WT, vehicle-treated n = 4; Hbbth3/+, n = 3 each group). (A–D, F–I) #P < 0.05 versus WT mice and *P < 0.05 versus vehicle-treated mice by 2-way ANOVA with Bonferroni multiple comparison correction.