title: Genetic profiling of dendritic cells exposed to live- or ultraviolet-irradiated Chlamydia muridarum reveals marked differences in CXC chemokine profiles.
abstract: Chlamydia trachomatis is a major cause of sexually transmitted disease worldwide for which an effective vaccine is being actively pursued. Current vaccine efforts will be aided by elucidating the interaction between Chlamydia and dendritic cells (DCs). Protective immunity appears to develop slowly following natural infection in humans, and early vaccine trials using inactivated C. trachomatis resulted in partial, short-lived protection with possible enhanced inflammatory pathology during re-infection. Thus, immunity following natural infection with live chlamydia may differ fundamentally from immune responses induced by immunization with inactivated chlamydia. We explored this conjecture by studying the response of DCs exposed to either viable or inactivated [ultraviolet (UV) -irradiated] chlamydia elementary bodies (EBs; designated as Live-EB and UV-EB, respectively) using Affymetrix GeneChip microarrays. Thirty-one immunologically characterized genes were differentially expressed by DCs following exposure to Live-EB or UV-EB, including two glutamic acid-leucine-arginine cysteine-X-cysteine (ELR CXC) neutrophil chemoattractant chemokines, Cxcl1 (KC), and Cxcl2 (MIP-2). Up-regulation of these genes by Live-EB as compared to UV-EB was verified by quantitative reverse transcription-polymerase chain reaction and increased chemokine secretion was confirmed by enzyme-linked immunosorbent assay both in vitro and in vivo. Immunofluorescence and fluorescence-activated cell sorter analysis of chlamydia-infected lung tissue confirmed that Live-EB but not UV-EB induced significant DC and neutrophil infiltration during infection. These observations demonstrate that the development of an antichlamydial immune response is dramatically influenced by chlamydial viability. This has implications as to why early inactivated chlamydial vaccines were ineffective and suggests that new vaccine design efforts may benefit from in vitro DC screening for ELR chemokine expression profiles.
authors.affiliation: University of British Columbia Centre for Disease Control, Vancouver, BC, Canada.
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Zaharik
authors.forename: Tarun
authors.initials: T
authors.lastname: Nayar
authors.forename: Rick
authors.initials: R
authors.lastname: White
authors.forename: Caixia
authors.initials: C
authors.lastname: Ma
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Vallance
authors.forename: Nadine
authors.initials: N
authors.lastname: Straka
authors.forename: Xiaozhou
authors.initials: X
authors.lastname: Jiang
authors.forename: Jose
authors.initials: J
authors.lastname: Rey-Ladino
authors.forename: Caixia
authors.initials: C
authors.lastname: Shen
authors.forename: Robert C
authors.initials: RC
authors.lastname: Brunham
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000276:immunology*; D001428:Bacterial Vaccines / Q000276:immunology; D002478:Cells, Cultured; D019743:Chemokines, CXC / Q000096:biosynthesis*; D002690:Chlamydia Infections / Q000276:immunology*; D023502:Chlamydia muridarum / Q000276:immunology* / Q000528:radiation effects; D003713:Dendritic Cells / Q000276:immunology*; D005260:Female; D015870:Gene Expression; D020869:Gene Expression Profiling / Q000379:methods; D051379:Mice; D008810:Mice, Inbred C57BL; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D018410:Pneumonia, Bacterial / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D015164:Vaccines, Inactivated / Q000276:immunology
chemical_list: D000942:Antigens, Bacterial; D001428:Bacterial Vaccines; D019743:Chemokines, CXC; D015164:Vaccines, Inactivated