title: Immunopathological effects of malaria pigment or hemozoin and other crystals.
abstract: Blood-stage malaria parasites produce insoluble hemozoin (Hz) crystals that are released in the blood circulation upon schizont rupture. In general, endogenous crystal formation or inhalation of crystalline materials is often associated with pathology. As the immune system responds differently to crystalline particles than to soluble molecules, in this review, the properties, immunological recognition, and pathogenic responses of Hz are discussed, and compared with two other major pathogenic crystals, monosodium urate (MSU) and asbestos. Because of the size and shape of MSU crystals and asbestos fibers, phagolysosomal formation is inefficient and often results in leakage of lysosomal content in the cell cytoplasm and/or in the extracellular environment with subsequent cell damage and cell death. Phagolysosomal formation after Hz ingestion is normal, but Hz remains stored inside these cells for months or even longer without any detectable degradation. Nonetheless, the different types of crystals are recognized by similar immune receptors, involving Toll-like receptors, the inflammasome, antibodies, and/or complement factors, and through similar signaling cascades, they activate both proinflammatory and anti-inflammatory immune responses that contribute to inflammation-associated pathology.
authors.affiliation: Laboratory of Immunobiology, Rega Institute for Medical Research, KU Leuven - University of Leuven, Leuven, Belgium.
authors.forename: Ariane
authors.initials: A
authors.lastname: Tyberghein
authors.forename: Katrien
authors.initials: K
authors.lastname: Deroost
authors.forename: Evelin
authors.initials: E
authors.lastname: Schwarzer
authors.forename: Paolo
authors.initials: P
authors.lastname: Arese
authors.forename: Philippe E
authors.initials: PE
authors.lastname: Van den Steen
mesh_terms: D000818:Animals; D001194:Asbestos / Q000276:immunology; D003460:Crystallization; D006420:Hemeproteins / Q000276:immunology*; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D008288:Malaria / Q000276:immunology*; D010860:Pigments, Biological / Q000276:immunology; D010961:Plasmodium / Q000276:immunology; D011687:Purines / Q000378:metabolism; D015398:Signal Transduction; D014527:Uric Acid / Q000276:immunology
chemical_list: D006420:Hemeproteins; D018836:Inflammation Mediators; D010860:Pigments, Biological; D011687:Purines; D001194:Asbestos; D014527:Uric Acid; C020753:hemozoin
keywords: asbestos; hemozoin; immune recognition; malaria pigment; monosodium urate; signal transduction