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Letters to the Editor
ciency. Glucose-6-phosphodehydrogenase and pyruvate kinase activity and hemoglobin electrophoresis were nor- mal. There was no report of bleeding. Patients II1 and II3 had similar total erythrocyte porphyrin levels but their chromatographic profiles showed mainly URO and COPRO in subject II1, and 92% PPIX (zinc PPIX 73%) in subject II3, as observed in the patient treated with phle- botomies (Figure 2B). Patient II4, a 2-month-old baby, was free of skin symptoms but had normocytic anemia with moderate hemolysis. His ferritin levels were quite high at 165 μg/L. He had increased plasma and urine por- phyrin levels.
To investigate the role of iron in the rate of porphyrin production we differentiated erythroid cells, derived from our patient’s peripheral CD34+ cells, by adapting the protocol of Mirmiran et al.7 by varying the holo-transfer- rin concentration from 20 to 2000 mg/mL (Online Supplementary Table S1). Blood was obtained from the CEP patient’s phlebotomy. Erythroid differentiation was monitored by flow cytometry using anti-CD36 and anti- CD235. Differentiation was similar in every condition of holo-transferrin concentration (Online Supplementary Figures S1 and S2). Total erythroid cell porphyrin meas- urements showed an increase in porphyrin levels, with approximately twice the level of porphyrin in the 700 mg/mL holo-transferrin condition, compared to the 200 mg/mL condition (Figure 3A). At higher concentra- tions (1000, 1500 and 2000 mg/mL), there were slight decreases in porphyrin levels, probably due to iron toxic- ity. Chromatography revealed that the higher levels of porphyrins were due to increases in URO and COPRO production, while PPIX levels remained stable (Figure 3B). These data show that CEP erythroid cells produce less URO and COPRO and that the proportion of PPIX increases when iron is less available. Thus, the in vitro findings confirm the in vivo observations that URO and COPRO levels decreased when the iron store was deplet- ed.
Treatment options for CEP patients are scarce. Photomutilation is prevented by sun avoidance. Hemolytic anemia is managed by hypertransfusions to decrease hematopoiesis and thereby porphyrin produc- tion.8 This treatment has limited success and is responsi- ble for severe secondary hemochromatosis.5 Patients often require BMT.9 An iron chelator (deferasirox) was successfully used to treat a patient with CEP who showed improved photosensitivity and erythropoiesis.4 The use of an iron chelator is a suitable treatment under iron overload, but its benefit and toxicity have not been evaluated in normal and iron-deficient states. Chronic deferasirox use is associated with toxicities such as gas- trointestinal hemorrhage and renal and liver failure.10 Conversely, phlebotomies have been safely used as a long-term treatment in adults and children with hemo- globin SC disease to reduce blood viscosity.11,12 Nevertheless, an iron chelator could be used initially to deplete iron stores. Phlebotomy could then be used to maintain low ferritin levels. This sequential strategy would avoid initial induction of erythropoiesis and the long-term toxicity of iron chelators. After decreasing her iron stores, our patient’s urine porphyrin levels reached a level close to that observed in CEP patients after BMT.13 Iron-deficiency anemia was partially compensat- ed by the correction of the hemolysis and the patient’s hemoglobin concentration remained above 10 g/dL. Finally, the observation of siblings with contrasting phe- notypes modulated by iron availability highlights the importance of iron regulation in CEP. This study strengthens the hypothesis that the heme biosynthesis
pathway can be slowed by inducing a mild iron-deficien- cy anemia. This is likely achieved by decreasing ALAS2 mRNA translation.4 More ALAS2 expression studies need to be performed to conclusively confirm this mech- anism.14 We can thus propose phlebotomies as a simple, universally available, well-tolerated and inexpensive strategy for treating CEP. Phlebotomies should be used in patients with hemolytic anemia without need of chronic transfusion or when BMT is not available, the latter remaining the first-line treatment in transfusion- dependent patients.
Arienne Mirmiran,1* Antoine Poli,1-3* Cecile Ged,4,5 Caroline Schmitt,1-3 Thibaud Lefebvre,1-3 Hana Manceau,1,2,6 Raêd Daher,1-3 Boualem Moulouel,3
Katell Peoc'h,1,2,6 Sylvie Simonin,1,3 Jean-Marc Blouin,4,5
1-3 1 1-3 Jean-Charles Deybach, Gaël Nicolas, Hervé Puy,
4,5 # 1-3,5# Emmanuel Richard and Laurent Gouya
1Institut National de la Santé et de la Recherche Médicale U1149, Centre de Recherches sur l’Inflammation, Paris; 2Université de Paris, Paris; 3Assistance Publique-Hôpitaux de Paris, Centre Français des Porphyries, Hôpital Louis Mourier, Colombes; 4Université Bordeaux, INSERM, BMGIC, U1035, CHU Bordeaux, Bordeaux; 5Laboratory of Excellence Gr-Ex, Paris and 6Assistance Publique-Hôpitaux de Paris, HUPNVS, Laboratoire de Biochimie, Hôpital Beaujon, Clichy, France
*AM and AP contributed equally as co-first authors.
#ER and LG contributed equally as co-senior authors. Correspondence:
LAURENT GOUYA - laurent.gouya@inserm.fr EMMANUEL RICHARD - emmanuel.richard@u-bordeaux.fr doi:10.3324/haematol.2019.228270
Disclosures: no conflicts of interest to disclose.
Contributions: AP, AM and LG wrote the manuscript. HP, JCD, CG, ER and LG designed the protocol and experiments. LG fol- lowed the patients’ clinical courses. AP, AM, CS, TL, SS and KP performed the biochemistry studies and cell cultures. CG, JMB and ER performed the molecular studies. All authors analyzed the data and edited the manuscript.
Acknowledgments: the authors thank the affected individuals and their families who kindly contributed to this study and Dr N Talbi who helped greatly with monitoring the patient.
Funding; this study was supported by a grant from Laboratory of Excellence GR-Ex, reference ANR-11-LABX-0051. AM was supported by a Labex GR-Ex scholarship. The Labex GR-Ex is funded by the program ‘‘Investissements d’avenir’’ of the French National Research Agency, reference ANR-11-IDEX-0005-02.
References
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