Hemozoin (Hz) is released into the blood stream after rupture of infected red blood cells (iRBCs) at the end of each parasite replication cycle. This free Hz is ingested by circulating and resident phagocytes. The presence of Hz in tissues after clearance of infection has been previously reported. Still, little is known about the kinetics of Hz in vivo, during and after Plasmodium infection. It is particularly important to understand Hz kinetics after malaria infections as it has been reported that Hz is associated with impairment of immune functions, including possible consequences for coinfections. Indeed, if Hz remains biologically active for prolonged periods of time inside immunocompetent cells, the potential consequences of such accumulation and presence to the immune system should be clarified. Here, using several independent methods to assess the presence of Hz, we report the long-term in vivo kinetics of Hz in diverse organs in a murine model of malaria infection. 1. Introduction In malaria, at the end of each Plasmodium replication cycle, infected red blood cells (iRBCs) rupture and release merozoites, together with hemozoin (Hz), into the blood stream. At that stage, up to 80–90% of all haem iron is localized in the digestive food vacuole and more than 95% of this haem has been converted to Hz [1]. On the basis of these findings and other reports, it has been calculated that, on average, 0.2–2？grams of Hz are produced during each erythrocytic cycle, assuming a 1–10% parasitaemia [2, 3]. Hz is ingested by circulating and resident phagocytes. One study investigated the percentage of Hz-containing granulocytes and monocytes in circulation as a predictor of disease outcome [4], while another reported median half-lives of 72？hours for Hz-containing granulocytes and 216 hours for Hz-containing monocytes in circulation [5]. Although the prolonged presence of Hz in tissues of individuals that had suffered from Plasmodium infections has been reported since the 19th century [6, 7], little is known about the long-term kinetics of Hz in vivo. How and over what period is Hz ultimately eliminated? To our knowledge, only one study in mice tried to address this question using a fluorometric method [8]. This report showed that 70% of Hz disappeared from the liver over 270 days after parasite clearance, while the amount of Hz in the spleen increased 8-fold. The importance of understanding Hz kinetics lies in the reported effects of Hz in impairment of immunity [9–14], including possible consequences for coinfections, such as tuberculosis [15]. Moreover, if Hz
References
[1]
T. J. Egan, J. M. Combrinck, J. Egan et al., “Fate of haem iron in the malaria parasite Plasmodium falciparum,” Biochemical Journal, vol. 365, no. 2, pp. 343–347, 2002.
[2]
F. Omodeo-Salè, A. Motti, A. Dondorp, N. J. White, and D. Taramelli, “Destabilisation and subsequent lysis of human erythrocytes induced by Plasmodium falciparum haem products,” European Journal of Haematology, vol. 74, no. 4, pp. 324–332, 2005.
[3]
D. E. Goldberg, A. F. G. Slater, A. Cerami, and G. B. Henderson, “Hemoglobin degradation in the malaria parasite Plasmodium falciparum: an ordered process in a unique organelle,” Proceedings of the National Academy of Sciences of the United States of America, vol. 87, no. 8, pp. 2931–2935, 1990.
[4]
P. G. Kremsner, C. Valim, M. A. Missinou et al., “Prognostic value of circulating pigmented cells in African children with malaria,” Journal of Infectious Diseases, vol. 199, no. 1, pp. 142–150, 2009.
[5]
N. P. J. Day, T. D. Pham, T. L. Phan et al., “Clearance kinetics of parasites and pigment-containing leukocytes in severe malaria,” Blood, vol. 88, no. 12, pp. 4694–4700, 1996.
[6]
H. Meckel, “Ueber schwarzes Pigment in der Milz und dem Blute einer Geisteskranken,” Zeitschr für Psychiatrie, vol. 4, pp. 198–226, 1847 (German).
[7]
R. Virchow, “Zur pathologischen Physiologie des Bluts,” Archiv für Pathologische Anatomie und Physiologie und für Klinische Medicin, vol. 2, no. 3, pp. 587–598, 1849.
[8]
M. A. Levesque, A. D. Sullivan, and S. R. Meshnick, “Splenic and hepatic hemozoin in mice after malaria parasite clearance,” Journal of Parasitology, vol. 85, no. 3, pp. 570–573, 1999.
[9]
E. Schwarzer, O. Müller, P. Arese, W. G. Siems, and T. Grune, “Increased levels of 4-hydroxynonenal in human monocytes fed with malarial pigment hemozoin. A possible clue for hemozoin toxicity,” The FEBS Letters, vol. 388, no. 2-3, pp. 119–122, 1996.
[10]
P. Deshpande and P. Shastry, “Modulation of cytokine profiles by malaria pigment—hemozoin: role of IL-10 in suppression of proliferative responses of mitogen stimulated human PBMC,” Cytokine, vol. 28, no. 6, pp. 205–213, 2004.
[11]
O. R. Millington, C. di Lorenzo, R. S. Phillips, P. Garside, and J. M. Brewer, “Suppression of adaptive immunity to heterologous antigens during Plasmodium infection through hemozoin-induced failure of dendritic cell function,” Journal of Biology, vol. 5, no. 2, article 5, 2006.
[12]
B. C. Urban and S. Todryk, “Malaria pigment paralyzes dendritic cells,” Journal of Biology, vol. 5, no. 2, article 4, 2006.
[13]
G. A. Awandare, Y. Ouma, C. Ouma et al., “Role of monocyte-acquired hemozoin in suppression of macrophage migration inhibitory factor in children with severe malarial anemia,” Infection and Immunity, vol. 75, no. 1, pp. 201–210, 2007.
[14]
O. R. Millington, V. B. Gibson, C. M. Rush et al., “Malaria impairs T cell clustering and immune priming despite normal signal 1 from dendritic cells,” PLoS Pathogens, vol. 3, no. 10, pp. 1380–1387, 2007.
[15]
M. Hawkes, X. Li, M. Crockett et al., “Malaria exacerbates experimental mycobacterial infection in vitro and in vivo,” Microbes and Infection, vol. 12, no. 11, pp. 864–874, 2010.
[16]
R. Frita, M. Rebelo, A. Pamplona et al., “Simple flow cytometric detection of haemozoin containing leukocytes and erythrocytes for research on diagnosis, immunology and drug sensitivity testing,” Malaria Journal, vol. 10, article 74, 2011.
[17]
C. Romagosa, C. Menendez, M. R. Ismail et al., “Polarisation microscopy increases the sensitivity of hemozoin and Plasmodium detection in the histological assessment of placental malaria,” Acta Tropica, vol. 90, no. 3, pp. 277–284, 2004.
[18]
B. R. Moore, J. D. Jago, and K. T. Batty, “Plasmodium berghei: parasite clearance after treatment with dihydroartemisinin in an asplenic murine malaria model,” Experimental Parasitology, vol. 118, no. 4, pp. 458–467, 2008.
[19]
A. D. Sullivan, I. Ittarat, and S. R. Meshnick, “Patterns of haemozoin accumulation in tissue,” Parasitology, vol. 112, part 3, pp. 285–294, 1996.
[20]
C. Casals-Pascual, O. Kai, J. O. P. Cheung et al., “Suppression of erythropoiesis in malarial anemia is associated with hemozoin in vitro and in vivo,” Blood, vol. 108, no. 8, pp. 2569–2577, 2006.
[21]
L. J. Carvalho, M. F. Ferreira-da-Cruz, C. T. Daniel-Ribeiro, M. Pelajo-Machado, and H. L. Lenzi, “Germinal center architecture disturbance during Plasmodium berghei ANKA infection in CBA mice,” Malaria Journal, vol. 6, article 59, 2007.
[22]
A. W. Suttie, “Histopathology of the spleen,” Toxicologic Pathology, vol. 34, no. 5, pp. 466–503, 2006.
[23]
F. Geissmann, M. G. Manz, S. Jung, M. H. Sieweke, M. Merad, and K. Ley, “Development of monocytes, macrophages, and dendritic cells,” Science, vol. 327, no. 5966, pp. 656–661, 2010.
[24]
R. Newton, Macrophagehalf-life, 1995, http://www.bionet/bionet/mm/immuno/1995-October/005776.html.
[25]
K. E. Lyke, D. A. Diallo, A. Dicko et al., “Association of intraleukocytic Plasmodium falciparum malaria pigment with disease severity, clinical manifestations, and prognosis in severe malaria,” The American Journal of Tropical Medicine and Hygiene, vol. 69, no. 3, pp. 253–259, 2003.
[26]
T. H？nscheid, M. L？ngin, B. Lell et al., “Full blood count and haemozoin-containing leukocytes in children with malaria: diagnostic value and association with disease severity,” Malaria Journal, vol. 7, article 109, 2008.
[27]
T. H？nscheid, R. Frita, M. L？ngin, P. G. Kremsner, and M. P. Grobusch, “Is flow cytometry better in counting malaria pigment-containing leukocytes compared to microscopy?” Malaria Journal, vol. 8, no. 1, article 255, 2009.
[28]
A. A. Lamikanra, M. Theron, T. W. A. Kooij, and D. J. Roberts, “Hemozoin (malarial pigment) directly promotes apoptosis of erythroid precursors,” PLoS One, vol. 4, no. 12, Article ID e8446, 2009.
[29]
G. Noel, X. Guo, Q. Wang, S. Schwemberger, D. Byrum, and C. Ogle, “Postburn monocytes are the major producers of TNF-α in the heterogeneous splenic macrophage population,” Shock, vol. 27, no. 3, pp. 312–319, 2007.
[30]
T. H？nscheid, T. J. Egan, and M. P. Grobusch, “Haemozoin: from melatonin pigment to drug target, diagnostic tool, and immune modulator,” Lancet Infectious Diseases, vol. 7, no. 10, pp. 675–685, 2007.
[31]
M. T. Shio, F. A. Kassa, M. J. Bellemare, and M. Olivier, “Innate inflammatory response to the malarial pigment hemozoin,” Microbes and Infection, vol. 12, no. 12-13, pp. 889–899, 2010.
[32]
M. Troye-Blomberg and K. Berzins, “Immune interactions in malaria co-infections with other endemic infectious diseases: implications for the development of improved disease interventions,” Microbes and Infection, vol. 10, no. 9, pp. 948–952, 2008.
