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Dr.Cristian Romeo Revnic*, Bogdan Păltineanu**, Cătălina Pena*, Speranța Prada*, Gabriel Ovidiu Dinu***, Gabriel Prada***
*Ambroise Pare` Hospital, University of Medicine, ParisVI, France
**NIGG ”Ana Aslan”
***UMF ”Carol Davila”
Rezumat
Lucrarea de fata trece in revista datele din literatura privitoare la eriptoza (moartea programata a eritrocitelor) care este realizata printr-o masinarie complexa, care implica anumite canale ionice si o varietate de molecule semnalizatoare. Eriptoza este stimulata intr-o mare varietate de boli de catre un mare numar de regulatori endogeni si xenobiotice. Patologiile asociate cu reiptoza accelerata includ: starile septice, malaria, sickle cell anemia, talasemia, deficienta in glucozo-6 fosfat dehidrogenaza, depletia de fosfat, deficitul de fier, sindromul uremic si boala Wilson. Eriptoza permite eritrocitelor defecte sa scape de hemoliza, dar pe de alta parte eriptoza excesiva favorizeaza dezvoltarea anemiei. De aceea, un echilibru sensibil trebuie sa existe intre mecanismele proeriptotice si antieriptotice pentru a mentine un numar adecvat de eritrocite circulante si in felul acesta sa se evite moartea non-eriptotica a eritrocitelor lezate.
Cuvinte cheie: eriptoza, apoptoza, hemoliza, eritrocite, anemia, starea septica, malaria
Abstract
This paper is dealing with the review of the literature data abaout eryptosis ,the programed cell death of erythrocytes which is is accomplished by a complex machinery involving ion channels and a variety of signaling molecules. Eryptosis is stimulated in a wide variety of diseases and by a large number of endogenous regulators and xenobiotics.
Diseases associated with accelerated eryptosis include sepsis, malaria, sickle-cell anemia, b-thalassemia, glucose-6-phosphate dehydrogenase (G6PD)-deficiency, phosphate depletion, iron deficiency,hemolytic uremic syndrome and Wilsons disease.
Eryptosis allows defective erythrocytes to escape hemolysis, but,on the other hand, excessive eryptosis favours the development of anemia. Thus, a delicate balance between proeryptotic and antieryptotic mechanisms is required to maintain an adequate number of circulating erythrocytes and yet avoid noneryptotic death of injured erythrocytes.
Key words erypthosis, apoptosis, hemolysis; red blood cells; anemia; sepsis; malaria.
INTRODUCTION
I tis known taht an adult human organism harvests more than 30 trillion erythrocytes, which comprise approximately one quarter of the total cell number. Moreover, the gross erythrocyte volume exceeds 2 L, that is, almost 10% of total cell volume. Thus, erythrocytes are among the most abundant cell types in a human body. The life span of erythrocytes amounts to some 100–120 days, that is, each day more than 200 billion erythrocytes need to be replaced, containing almost 20 mL of packed cell volume[1]..
Erythrocytes are considered to undergo senescence eventually resulting in the clearance of aged erythrocytes [2]. Beyond that, erythrocytes are, similar to nucleated cells, cleared by suicidal death.[3].
Suicidal cell death accomplishes the disposal of abundant, defective, or potentially harmful cells . Suicidal death of nucleated cells or apoptosis [4] is characterised by loss of
cellular K1 with cell shrinkage, nuclear condensation, DNA fragmentation, mitochondrial depolarization, cell membrane blebbing and breakdown of phosphatidylserine asymmetry of
the plasma membrane . Thus, apoptosis allows the elimination of those cells without release of intracellular proteins which would otherwise cause inflammation .
Erythrocytes lack nuclei and mitochondria, critical elements in the machinery of apoptosis. Thus, dying erythrocytes were considered to be eliminated by mechanisms other than apoptosis.[5]
Accounting for the differences from and similarities to apoptosis, the term eryptosis has been coined to describe the suicidal erythrocyte death [6]. The following synopsis will briefly
describe the triggers and inhibitors, the signalling and the (patho) physiological significance of eryptosis. Presently, we are only beginning to understand the complex machinery and importance of this fundamental cellular mechanism.
TRIGGERS OF ERYPTOSIS
Among the triggers of eryptosis are included: osmotic shock [7], oxidative stress [8] and energy depletion . Suicidal erythrocyte death could be triggered by ligation of specific surface antigens, such as glycophorin-C (41), the thrombospondin-1 receptor CD47 [9]. and the death receptor CD95/Fas . Further stimulators of eryptosis include ceramide (acylsphingosine) , prostaglandin E2 [10]. platelet activating factor, anti A IgG antibodies , hemolysin from Vibrio parahaemolyticus, listeriolysin paclitaxel , amantadine, azathioprine , retinoic acid , chlorpromazine , cyclosporine , methylglyoxal[11]), amyloid peptides , anandamide , Bay-Y5884 , curcumin , valinomycin aluminium , mercury , lead , gold , vanadium and copper [12].
The increase in erythrocyte cytosolic Ca21 concentration further stimulates Ca21-sensitive K1 channel The subsequent efflux of K1 hyperpolarises the cell membrane, which
drives Cl2 exit in parallel to K1 . The cellular loss of KCl with osmotically obliged water leads to cell shrinkage, which further augments the stimulation of cell membrane scrambling.
The Ca21 sensitivity of cell membrane scrambling could be enhanced by ceramide, which, similar to increased cytosolic Ca21 activity, increases phosphatidylserine exposure . Ceramide formation is stimulated by platelet activating factor (PAF), which activates a sphingomyelinase leading to the breakdown of sphingomyelin [12]. Accordingly, eryptosis following osmotic shock is blunted by the sphingomyelinase inhibitor 3,4- dichloroisocoumarin, by genetic knockout of PAF receptors (PAF receptor knockout mice) and by the PAF receptor antagonist ABT491[12].. To be effective, PAF does not require elevated cytosolic Ca21 concentrations, that is, PAF at least partially accounts for Ca21-independent eryptosis [12].
Besides its effect on cell membrane scrambling, PAF activates Ca21-sensitive K1 channels in the erythrocyte cell membrane by sensitizing them for the stimulating effects of cytosolic
Ca21 [13]. Conversely, PAF is released from erythrocyte progenitor cells upon increase in the cytosolic Ca21 activity.
The stimulation of eryptosis by energy depletion involves activation of PKC and PKC-dependent phosphorylation of membrane proteins with subsequent phosphatidylserine exposure and cell shrinkage . The effects of energy depletion are mimicked by stimulation of PKC with phorbolesters or inhibition of protein phosphatases such as okadaic acid. Protein kinase C (PKC) activation results in stimulation of erythrocyte Ca21 entry and phosphatidylserine exposure Erythrocytes express PKCa, PKCi, PKCl and PKCf [14], which phosphorylate cytoskeletal proteins, such as band 4.1, 4.9 and adducin and the human Na1/H1 antiporter NHE 1 .[14].
Oxidative stress or defects of antioxidative defence elicit eryptosis in part by stimulating Ca21 entry via activation of the Ca21 permeable cation channels . Oxidative stress further activates erythrocyte Cl2 channels, which are required for erythrocyte shrinkage and thus also participate in the triggering of eryptosis [15]. The stimulation of eryptosis by oxidative stress is paralleled by the activation of aspartyl and cysteinyl proteases . Erythrocytes express oxidant-sensitive caspases [15], which cleave the anion exchanger band 3 and stimulate phosphatidylserine exposure of erythrocytes . Eryptosis following ionomycin or hyperosmotic shock does, however, not require activation of caspases [15].
INHIBITORS OF ERYPTOSIS
Among the inhibitors of eryptosis are Ca21-permeable cation channels which have been shown in one study to be inhibited by erythropoietin [16]. Thus, the hormone does not only inhibit apoptosis of erythrocytic progenitor cells , but similarly blunts the suicidal death of mature erythrocytes. The antieryptotic effect of erythropoietin results in increased life span of circulating cells [16].
Eryptosis has further been shown to be inhibited by flufenamic acid , adenosine [17]. and nitroxide [18]. Nitroxide is partially effective through activation of cGMP-dependent
protein kinases [18]. The mechanism is apparently effective under control conditions in vivo, as mice deficient of the cGMP-dependent protein kinase type I (cGKI) suffer from
severe anaemia and splenomegaly .
Erythrocytes participate in the regulation of nitric oxide (NO) formation [18]. Oxygenated hemoglobin binds and desoxygenated S-Nitrosohemoglobin releases NO[19]. The release of NO from desoxygenated erythrocytes contributes to vasodilation and counteracts suicidal erythrocyte death in hypoxic tissue. Along those lines, impaired NO formation in NO-depleted banked erythrocytes is considered to cause vasoconstriction and ischemia following transfusion [19]
Moreover defective erythrocyte NO release may contribute to pulmonary hypertension and deranged microcirculation in sickle cell anemia [20].
PHYSIOLOGICAL FUNCTIONS OF ERYPTOSIS
Eryptosis is engaged into many physiological functions which leads to removal of injured erythrocytes prior to hemolysis. Cell injury, such as energy depletion, defective Na1/ K1ATPase or enhanced leakiness of the cell membrane leads
eventually to cellular gain of Na1 and Cl2 and osmotically obliged water with subsequent cell swelling [21]. Initially, the entry of Na1 is compensated by cellular loss of K1. However,
the cellular K1 loss decreases the K1 equilibrium potential eventually leading to gradual depolarization. The loss of electrical gradient across the cell membrane favours Cl2 entry, which is followed by osmotically obliged water. The resulting cell swelling jeopardises the integrity of the cell membrane. Excessive cell swelling leads to rupture of the cell membrane with release of cellular hemoglobin, which may be filtered in the renal glomerula thus occluding renal tubules. Hemolysis is prevented,if cell swelling is preceded by eryptosis. Phosphatidylserine exposure at the cell surface of eryptotic cells is recognised by macrophages, which clear phosphatidylserine-exposing defective erythrocytes from circulating blood prior to hemolysis.
Any acceleration of eryptosis limits the life span of parasites within the infected erythrocytes and thus counteracts the growth of parasites. Sickle-cell trait, b-thalassemia-trait, homozygous
Hb-C and G6PD-deficiency lead to premature senescence and/or eryptosis upon infection with Plasmodium thus resulting in to accelerated clearance of ring stage-infected erythrocytes Moreover, iron deficiency [22] and lead blunt parasitemia and enhance the survival of Plasmodium bergheiinfected mice presumably by accelerating erythrocyte death.
THE CASE OF NEWBORNS
Neonatal erythrocytes mainly contain HbF [23].. The high affinity of HbF supports oxygen uptake in the placenta. The high oxygen affinity of HbF is not required for full oxygenation
of hemoglobin in the inflated lung but impairs oxygen release in the periphery. Thus, HbF is clearly functionally inappropriate for efficient gas exchange after birth. Fetal erythrocytes are
more resistant to Cl2 removal, osmotic shock, PGE2 and PAF, but are more sensitive to oxidative stress . The exquisite oxygen sensitivity of fetal erythrocytes fosters their removal upon inflation of the lung and exposure to inspired oxygen.
NEOCYTOLYSIS
Newly formed erythrocytes may be particularly sensitive to suicidal death, a phenomenon described as ‘neocytolysis’ [24].It is presently not clear whether neocytolysis involves the same mechanisms as eryptosis. Moreover, the mechanisms underlying the enhanced sensitivity of newly formed erythrocytes to suicidal cell death remain elusive. Those erythrocytes were significantly more resistant to osmotic lysis than WT erythrocytes
but more sensitive to the eryptotic effects of Cl2 removal and exposure to the Ca21 ionophore ionomycin [24]. In view of those observations the possibility was considered that erythropoietin stimulates the expression of genes in progenitor cells which render the erythrocytes more sensitive to eryptosis and leads to enhanced erythrocyte death as soon as the erythropoietin concentrations decline. The upregulation of proeryptotic effectors in erythrocytes under the influence of high erythropoietin concentrations would allow more rapid removal of excessive erythrocytes, if enhanced erythrocyte concentration is
no more needed and the plasma erythropoietin concentrations fall. This would allow to shorten a feedback regulation, which otherwise would take 120 days. Along those lines neocytolysis [24], the accelerated death of young erythrocytes following a limited exposure to high altitude or space flight, may reflect the death of those erythrocytes, which have been generated under high erythropoietin concentrations and are thus more vulnerable
to eryptosis. Clearly, additional experiments are needed to prove or disprove this speculation [24].
Eryptosis has been observed in a wide variety of clinical conditions, including sepsis [25], hemolytic uremic syndrome [26], renal insuficiency , malaria infection , sicklecell
anemia , b-thalassemia[27], glucose-6-phosphate dehydrogenase (G6PD)-deficiency [28], phosphate depletion and Wilsons disease [29]. Enhanced eryptosis in sepsis and hemolytic syndrome results from accumulation of eryptotic activity in plasma. Accordingly,
the addition of plasma from patients with sepsis [29] or hemolytic uremic syndrome [26] triggers eryptosis of erythrocytes from healthy individuals. In both clinical conditions, the exposure to plasma eventually increases ceramide formation. The shortened life span of iron-deficient erythrocytes is at least partially due to enhanced cation channel activity, presumably due to decreased volume of iron-deficient erythrocytes, which leads to activation of the channel . In Wilsons disease, a condition caused by Cu21-accumulation due to inactivating mutations of Cu21-secreting ATP7B” [30], Cu21 stimulates both, Ca21 entry and ceramide formation.
CONCLUSIONS
Erythrocytes in analogy to apoptosis of nucleated cells, could be cleared by eryptosis.
The suicidal death of erythrocytes is accomplished by a complex machinery involving ion channels and a variety of signaling molecules.
The threshold to trigger eryptosis is low. Accordingly, eryptosis is stimulated in a wide variety of diseases and by a large number of endogenous regulators and xenobiotics.
Clearly, future experiments are likely to disclose additional triggers and inhibitors of eryptosis and further signalling pathways participating in the regulation of this fundamental biological mechanism.
REFERENCES
1. Jelkmann W. Functional significance of erythrocytes. In: Lang F, Föller M, editors. Erythrocytes. London: Imperial College Press; 2012. in press
2 Bosman G. J., Willekens F. L., and Werre J. M. (2005) Erythrocyte aging: a more than superficial resemblance to apoptosis? Cell. Physiol.Biochem. 16, 1–8.
3.Lang F, Qadri SM. Mechanisms and significance of eryptosis, the suicidal death of erythrocytes. Blood Purif. 2012;33:125–130.
4. Gulbins E., Jekle A., Ferlinz K., Grassme H., and Lang F. (2000) Physiology of apoptosis. Am. J. Physiol. Renal. Physiol. 279, F605–F615.
5.Wlodkowic D, Telford W, Skommer J, Darzynkiewicz Z. Apoptosis and beyond: cytometry in studies of programmed cell death. Methods Cell Biol. 2011;103:55–98
6.Lang K. S., Lang P. A., Bauer C., Duranton C., Wieder T., Huber S. M., and Lang F6 (2005) Mechanisms of suicidal erythrocyte death. Cell. Physiol. Biochem. 15, 195–202.
7.Gatidis S, Zelenak C, Fajol A, Lang E, Jilani K, Michael D, Qadri SM, Lang F. p38 MAPK activation and function following osmotic shock of erythrocytes. Cell Physiol Biochem. 2011;28:1279–1286
8.Barvitenko N. N., Adragna N. C., and Weber R. E. (2005) Erythrocyte signal transduction pathways, their oxygenation dependence and functional significance. Cell. Physiol. Biochem. 15, 1–18.
9. Head D. J., Lee Z. E., Swallah M. M., and Avent N. D. (2005) Ligation of CD47 mediates phosphatidylserine expression on erythrocytes and a concomitant loss of viability in vitro. Br. J. Haematol. 130, 788–790.
10.Lang P. A., Kempe D. S., Myssina S., Tanneur V., Birka C., Laufer S., Lang F., Wieder T., and Huber S. M. (2005) PGE2 in the regulation of programmed erythrocyte death. Cell. Death. Differ. 12, 415–428
11. Nicolay J. P., Schneider J., Niemoeller O. M., Artunc F., Portero-Otin M., Haik G., Jr., Thornalley P. J., Schleicher E., Wieder T., and Lang F. (2006) Stimulation of suicidal erythrocyte death by methylglyoxal. Cell. Physiol. Biochem. 18, 223–232.
12.Lang P. A., Schenck M., Nicolay J. P., Becker J. U., Kempe D. S., Lupescu A., Koka S., Eisele K., Klarl B. A., Rubben H., Schmid K. W., Mann K., Hildenbrand S., Hefter H., Huber S. M., Wieder T., Erhardt A., Haussinger D., Gulbins E., and Lang F. (2007) Liver cell
death and anemia in Wilson disease involve acid sphingomyelinase and ceramide. Nat. Med. 13, 164–170.
13.. Rivera A., Jarolim P., and Brugnara C. (2002) Modulation of Gardos channel activity by cytokines in sickle erythrocytes. Blood 99, 357–603.
.14. Zelenak C, Eberhard M, Jilani K, Qadri SM, Macek B, Lang F. Protein kinase CK1alpha regulates erythrocyte survival. Cell Physiol Biochem. 2012;29:171–180.
15.Calderon-Salinas JV, Munoz-Reyes EG, Guerrero-Romero JF, Rodriguez-Moran M, Bracho-Riquelme RL, Carrera-Gracia MA, Quintanar-Escorza MA. Eryptosis and oxidative damage in type 2 diabetic mellitus patients with chronic kidney disease. Mol Cell Biochem. 2011;357:171–179
16. Myssina S., Huber S. M., Birka C., Lang P. A., Lang K. S., Friedrich B., Risler T., Wieder T., and Lang F. (2003) Inhibition of erythrocyte cation channels by erythropoietin. J. Am. Soc. Nephrol. 14, 2750–2757.
17Niemoeller O. M., Bentzen P. J., Lang E., and Lang F. (2007) Adenosine protects against suicidal erythrocyte death. Pflugers. Arch. 454, 427–439.
18.Nicolay J. P., Liebig G., Niemoeller O. M., Koka S., Ghashghaeinia M., Wieder T., Haendeler J., Busse R., and Lang F. (2008) Inhibition of suicidal erythrocyte death by nitric oxide. Pflugers Arch. 456, 293–305.
19.Angelo M., Singel D. J., and Stamler J. S. (2006) An S-nitrosothiol (SNO) synthase function of hemoglobin that utilizes nitrite as a substrate. Proc. Natl. Acad. Sci. USA 103, 8366–8371
20.Pawloski J. R., Hess D. T., and Stamler J. S. (2005) Impaired vasodilation by red blood cells in sickle cell disease. Proc. Natl. Acad. Sci. USA 102, 2531–2536.
21.Lang F., Busch G. L., Ritter M., Vo¨lkl H., Waldegger S., Gulbins E., and Ha¨ussinger D. (1998) Functional significance of cell volume regulatory mechanisms. Physiol. Rev. 78, 247–306.
22.Koka S., Foller M., Lamprecht G., Boini K. M., Lang C., Huber S. M., and Lang F. (2007) Iron deficiency influences the course of malaria in Plasmodium berghei infected mice. Biochem. Biophys. Res. Commun. 357, 608–614
23.Egberts J. and Van Pelt J. (2004) Evaluation of the blood analyzer ABL 735 radiometer for determination of the percentage of fetal hemoglobin in fetal and neonatal blood. Scand. J Clin. Lab. Invest. 64, 128–131.
24.Rice L. and Alfrey C. P. (2005) The negative regulation of red cell mass by neocytolysis: physiologic and pathophysiologic manifestations.Cell. Physiol. Biochem. 15, 245–250
25. Kempe D. S., Akel A., Lang P. A., Hermle T., Biswas R., Muresanu J., Friedrich B., Dreischer P., Wolz C., Schumacher U., Peschel A.,Gotz F., Doring G., Wieder T., Gulbins E., and Lang F. (2007) Suicidal erythrocyte death in sepsis. J. Mol. Med. 85, 269–277.
26. Lang P. A., Beringer O., Nicolay J. P., Amon O., Kempe D. S., Hermle T., Attanasio P., Akel A., Schafer R., Friedrich B., Risler T., Baur M., Olbricht C. J., Zimmerhackl L. B., Zipfel P. F., Wieder T., and Lang F. (2006) Suicidal death of erythrocytes in recurrent hemolytic uremic syndrome. J. Mol. Med. 84, 378–388.
27. Ayi K., Turrini F., Piga A., and Arese P. (2004) Enhanced phagocytosis of ring-parasitized mutant erythrocytes: a common mechanism that may explain protection against falciparum malaria in sickle trait and b-thalassemia trait. Blood 104, 3364–3371
28Lang K. S., Roll B., Myssina S., Schittenhelm M., Scheel-Walter H. G., Kanz L., Fritz J., Lang F., Huber S. M., and Wieder T. (2002) Enhanced erythrocyte apoptosis in sickle cell anemia, thalassemia and glucose-6-phosphate dehydrogenase deficiency. Cell. Physiol. Biochem.12, 365–372.
29. Lang P. A., Schenck M., Nicolay J. P., Becker J. U., Kempe D. S., Lupescu A., Koka S., Eisele K., Klarl B. A., Rubben H., Schmid K. W., Mann K., Hildenbrand S., Hefter H., Huber S. M., Wieder T., Erhardt A., Haussinger D., Gulbins E., and Lang F. (2007) Liver cell death and anemia in Wilson disease involve acid sphingomyelinase and ceramide. Nat. Med. 13, 164–170.
30. Gitlin J. D. (2003) Wilson disease. Gastroenterology 125, 1868–1877 Egberts J. and Van Pelt J. (2004) Evaluation of the blood analyzer
ABL 735 radiometer for determination of the percentage of fetal hemoglobin
in fetal and neonatal blood. Scand. J Clin. Lab. Invest. 64
