title: Toxoplasma gondii induces changes in intracellular calcium in macrophages.
abstract: Toxoplasma gondii is an obligate intracellular parasite that interacts with calcium storage organelles and induces calcium-dependent signalling in macrophages. This study was performed to determine whether Toxoplasma induces changes in intracellular calcium in these cells. Ratiometric imaging of live, Fura-2 loaded macrophages challenged with T. gondii revealed robust elevations in intracellular calcium. These elevations were late in onset, beginning 15-20 min after addition of parasites and occurred in up to 20% of macrophages in an imaging field. Further characterization of these events revealed that they follow from challenge with live T. gondii, but not heat-killed parasites or soluble Toxoplasma antigen (STAg). Parasite-induced calcium elevations derived from extracellular sources, and were independent of host recognition factors MyD88 and CCR5. These findings indicate that Toxoplasma gondii alters calcium homeostasis in macrophages and this activity is independent of known pathways involved in the innate recognition of this organism.
authors.affiliation: Department of Pathobiology, School of Veterinary Medicine, Room 313, Hill Pavilion, 380 South University Avenue, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: K S
authors.initials: KS
authors.lastname: Masek
authors.forename: P
authors.initials: P
authors.lastname: Zhu
authors.forename: B D
authors.initials: BD
authors.lastname: Freedman
authors.forename: C A
authors.initials: CA
authors.lastname: Hunter
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D018946:Chemokine CCL5 / Q000235:genetics; D005260:Female; D008264:Macrophages / Q000378:metabolism* / Q000469:parasitology*; D051379:Mice; D008810:Mice, Inbred C57BL; D053594:Myeloid Differentiation Factor 88 / Q000235:genetics; D014122:Toxoplasma / Q000378:metabolism*
chemical_list: D018946:Chemokine CCL5; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; D002118:Calcium