title: Differential CD28 and inducible costimulatory molecule signaling requirements for protective CD4+ T-cell-mediated immunity against genital tract Chlamydia trachomatis infection.
abstract: Th1 cells and gamma interferon (IFN-gamma) production play critical roles in protective immunity against genital tract infections by Chlamydia trachomatis. Here we show that inducible costimulatory molecule (ICOS)(-/-) mice develop greatly augmented host resistance against chlamydial infection. Protection following a primary infection was characterized by strong Th1 immunity with enhanced CD4(+) T-cell-mediated IFN-gamma production in the genital tract and high expression of T-bet in the draining para-aortic lymph node. This Th1 dominance was associated with low expression of interleukin 10 (IL-10) mRNA in the uteruses of protected ICOS(-/-) mice. By contrast, CD28(-/-) mice were severely impaired in their adaptive immune response, demonstrating a lack of CD4(+) T cells and IFN-gamma in the genital tract, with a substantial delay in bacterial elimination compared to that seen in wild-type (WT) mice. Upon reinfection, WT mice exhibited a transient local infection with evidence of regulatory T-cell (Treg)/Foxp3 mRNA and a more balanced Th1 and Th2 response in the genital tract than ICOS(-/-) mice, whereas 90% of the latter mice developed sterile immunity, poor expression of local Treg/Foxp3 mRNA, and macroscopic signs of enhanced local immunopathology. Therefore, different requirements for CD28 signaling and ICOS signaling clearly apply to host protection against a genital tract infection by C. trachomatis. Whereas, CD28 signaling is critical, ICOS appears to be dispensable and can have a dampening effect on Th1 development by driving Th2 immunity and anti-inflammation through IL-10 production and promotion of the Foxp3(+) Treg populations in the genital tract. Both the CD28-deficient and the ICOS-deficient mice demonstrated poor specific antibody production, supporting the fact that antibodies are not needed for protection against genital tract chlamydial infections.
authors.affiliation: Department of Microbiology and Immunology, Mucosal Immunobiology and Vaccine Research Center, Institute of Biomedicine, Gothenburg University, Box 435, 40530 Gothenburg, Sweden.
authors.forename: Ellen
authors.initials: E
authors.lastname: Marks
authors.forename: Martina
authors.initials: M
authors.lastname: Verolin
authors.forename: Anneli
authors.initials: A
authors.lastname: Stensson
authors.forename: Nils
authors.initials: N
authors.lastname: Lycke
mesh_terms: D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte / Q000235:genetics / Q000502:physiology*; D018106:CD28 Antigens / Q000235:genetics / Q000502:physiology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000382:microbiology* / Q000473:pathology; D002690:Chlamydia Infections / Q000276:immunology* / Q000473:pathology; D002692:Chlamydia trachomatis / Q000276:immunology; D005260:Female; D006801:Humans; D007111:Immunity, Cellular; D060889:Inducible T-Cell Co-Stimulator Protein; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D015398:Signal Transduction / Q000276:immunology*; D018417:Th1 Cells / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D018418:Th2 Cells / Q000276:immunology / Q000382:microbiology / Q000473:pathology
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D018106:CD28 Antigens; C556692:ICOS protein, human; C556694:Icos protein, mouse; D060889:Inducible T-Cell Co-Stimulator Protein