title: Cryptosporidium infection of human intestinal epithelial cells increases expression of osteoprotegerin: a novel mechanism for evasion of host defenses.
abstract: Cryptosporidium parasites are pathogens of human intestinal epithelial cells. To determine which genes are regulated during early infection, human ileal mucosa cultured as explants was infected with C. parvum or C. hominis, and gene expression was analyzed by microarray. The gene for osteoprotegerin (OPG) was up-regulated by both parasites. OPG mRNA was also significantly increased in biopsy specimens obtained from a volunteer experimentally infected with C. meleagridis, compared with levels in a prechallenge biopsy specimen. After in vitro infection of HCT-8 cells, there was an early peak in production of OPG mRNA protein. Treatment of infected cells with the OPG ligand tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induced epithelial cell apoptosis and reduced parasite numbers, and recombinant OPG blocked these effects. These results suggest a novel TRAIL-mediated pathway for elimination of Cryptosporidium infection and a role for OPG in modulating this host response.
authors.affiliation: Infectious Disease Section, Department of Medicine, Baylor College of Medicine, Houston, TX, USA.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Castellanos-Gonzalez
authors.forename: Linda S
authors.initials: LS
authors.lastname: Yancey
authors.forename: Heuy-Ching
authors.initials: HC
authors.lastname: Wang
authors.forename: Birte
authors.initials: B
authors.lastname: Pantenburg
authors.forename: Kathleen R
authors.initials: KR
authors.lastname: Liscum
authors.forename: Dorothy E
authors.initials: DE
authors.lastname: Lewis
authors.forename: A Clinton
authors.initials: AC
authors.lastname: White
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D002478:Cells, Cultured; D003457:Cryptosporidiosis / Q000276:immunology* / Q000378:metabolism* / Q000469:parasitology; D003458:Cryptosporidium / Q000302:isolation & purification* / Q000502:physiology; D006790:Host-Parasite Interactions / Q000502:physiology; D006801:Humans; D007413:Intestinal Mucosa / Q000276:immunology* / Q000378:metabolism / Q000469:parasitology*; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D053244:Osteoprotegerin / Q000096:biosynthesis* / Q000276:immunology / Q000378:metabolism; D034421:Sus scrofa; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000037:antagonists & inhibitors / Q000276:immunology
chemical_list: D053244:Osteoprotegerin; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human