title: Synthetic Plasmodium-like hemozoin activates the immune response: a morphology - function study.
abstract: Increasing evidence points to an important role for hemozoin (HZ), the malaria pigment, in the immunopathology related to this infection. However, there is no consensus as to whether HZ exerts its immunostimulatory activity in absence of other parasite or host components. Contamination of native HZ preparations and the lack of a unified protocol to produce crystals that mimic those of Plasmodium HZ (PHZ) are major technical limitants when performing functional studies with HZ. In fact, the most commonly used methods generate a heterogeneous nanocrystalline material. Thus, it is likely that such aggregates do not resemble to PHZ and differ in their inflammatory properties. To address this issue, the present study was designed to establish whether synthetic HZ (sHZ) crystals produced by different methods vary in their morphology and in their ability to activate immune responses. We report a new method of HZ synthesis (the precise aqueous acid-catalyzed method) that yields homogeneous sHZ crystals (Plasmodium-like HZ) which are very similar to PHZ in their size and physicochemical properties. Importantly, these crystals are devoid of protein and DNA contamination. Of interest, structure-function studies revealed that the size and shape of the synthetic crystals influences their ability to activate inflammatory responses (e.g. nitric oxide, chemokine and cytokine mRNA) in vitro and in vivo. In summary, our data confirm that sHZ possesses immunostimulatory properties and underline the importance of verifying by electron microscopy both the morphology and homogeneity of the synthetic crystals to ensure that they closely resemble those of the parasite. Periodic quality control experiments and unification of the method of HZ synthesis are key steps to unravel the role of HZ in malaria immunopathology.
authors.affiliation: The Research Institute of the McGill University Health Centre, Centre for the Study of Host Resistance, Departments of Medicine, Microbiology and Immunology, McGill University, Montréal, Canada.
authors.forename: Maritza
authors.initials: M
authors.lastname: Jaramillo
authors.forename: Marie-Josée
authors.initials: MJ
authors.lastname: Bellemare
authors.forename: Caroline
authors.initials: C
authors.lastname: Martel
authors.forename: Marina Tiemi
authors.initials: MT
authors.lastname: Shio
authors.forename: Ana Paulina
authors.initials: AP
authors.lastname: Contreras
authors.forename: Marianne
authors.initials: M
authors.lastname: Godbout
authors.forename: Michel
authors.initials: M
authors.lastname: Roger
authors.forename: Eric
authors.initials: E
authors.lastname: Gaudreault
authors.forename: Jean
authors.initials: J
authors.lastname: Gosselin
authors.forename: D Scott
authors.initials: DS
authors.lastname: Bohle
authors.forename: Martin
authors.initials: M
authors.lastname: Olivier
mesh_terms: D000818:Animals; D002384:Catalysis; D002460:Cell Line; D003460:Crystallization; D006420:Hemeproteins / Q000378:metabolism*; D006427:Hemin / Q000737:chemistry; D006801:Humans; D007107:Immune System / Q000187:drug effects*; D051379:Mice; D008822:Mice, Transgenic; D008855:Microscopy, Electron, Scanning; D008954:Models, Biological; D016788:Plasmodium chabaudi / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014961:X-Ray Diffraction
chemical_list: D006420:Hemeproteins; C020753:hemozoin; D006427:Hemin