title: Pyridinylimidazole p38 mitogen-activated protein kinase inhibitors block intracellular Toxoplasma gondii replication.
abstract: Toxoplasma gondii is a medically important, obligate intracellular parasite. Little is known regarding factors that regulate its replication within cells. Such knowledge would further understanding of T. gondii pathogenesis, and might lead to novel therapeutic strategies. Mitogen-activated protein kinases (MAPKs) govern diverse cellular processes including proliferation and differentiation. We now show that treatment of T. gondii-infected cells with SB203580 or SB202190, substituted pyridinylimidazoles that are potent inhibitors of human p38 MAPK, inhibits intracellular T. gondii replication. Several independent experimental approaches suggest that the anti-proliferative effects of pyridinylimidazoles depend on direct action on tachyzoites, not the host cell: (i) selective inhibition of host p38 MAPK using recombinant adenoviruses had little effect on tachyzoite replication, (ii) pyridinylimidazole-treated tachyzoites developed abnormal morphology suggesting defective parasite division, and (iii) pyridinylimidazole-resistant mutant tachyzoites were developed through culture in progressively higher drug concentrations. We hypothesise that pyridinylimidazoles target a human p38 MAPK homologue in tachyzoites that regulates their replication. Phylogenetic data suggest that T. gondii likely encodes a p38 MAPK homologue, but such a homologue is absent from the incomplete Toxoplasma genomic data base. As all eukaryotic pathogens, including agents of malaria, leishmaniasis and trypanosomiasis encode endogenous MAPKs, drugs inhibiting endogenous MAPK activation may represent a novel, potentially broadly-acting class of anti-parasitic agents. Pyridinylimidazoles also represent tools to elucidate factors governing intracellular tachyzoite replication.
authors.affiliation: Tulane Medical School, Tulane University, 1430 Tulane Avenue, SL78, New Orleans, LA 70112, USA.
authors.forename: Shuang
authors.initials: S
authors.lastname: Wei
authors.forename: Florentina
authors.initials: F
authors.lastname: Marches
authors.forename: Ben
authors.initials: B
authors.lastname: Daniel
authors.forename: Sabrina
authors.initials: S
authors.lastname: Sonda
authors.forename: Kim
authors.initials: K
authors.lastname: Heidenreich
authors.forename: Tyler
authors.initials: T
authors.lastname: Curiel
mesh_terms: D000818:Animals; D002070:Butadienes / Q000494:pharmacology; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005347:Fibroblasts / Q000187:drug effects / Q000469:parasitology; D007093:Imidazoles / Q000494:pharmacology*; D020128:Inhibitory Concentration 50; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors*; D009154:Mutation / Q000235:genetics; D009570:Nitriles / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D014122:Toxoplasma / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development* / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D002070:Butadienes; D004791:Enzyme Inhibitors; D007093:Imidazoles; D009570:Nitriles; D011725:Pyridines; C465539:SB202494; C113580:U 0126; D002784:Cholesterol; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580; C090942:4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)imidazole