title: Expression of interferon-gamma and tumour necrosis factor-alpha messenger RNA does not correlate with protection in guinea pigs challenged with virulent Mycobacterium tuberculosis by the respiratory route.
abstract: Cytokine messenger RNA (mRNA) expression was investigated in the spleen and lung digest cells of bacillus Calmette-Guérin (BCG)-vaccinated and non-vaccinated guinea pigs following low-dose, pulmonary exposure to virulent Mycobacterium tuberculosis. After purified protein derivative (PPD) stimulation, the levels of lung cell interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha) and spleen cell interleukin-12 (IL-12) p40 mRNAs were significantly increased in the non-vaccinated M. tuberculosis-infected guinea pigs compared to the BCG-vaccinated guinea pigs. In contrast, the expression of anti-inflammatory transforming growth factor-beta and IL-10 mRNAs was significantly enhanced in the spleens of BCG-vaccinated animals. Despite the presence of protective cytokine mRNA expression, the non-vaccinated guinea pigs had significantly higher lung and spleen bacterial burdens. In contrast, BCG-vaccinated guinea pigs controlled the bacterial multiplication in their lungs and spleens, indicating that both protective as well as anti-inflammatory cytokine responses are associated with a reduction in bacteria. In addition, lung digest cells from non-vaccinated guinea pigs contained a significantly higher percentage of neutrophils, CD3(+) and CD8(+) T cells, while the percentage of macrophages was increased in the BCG-vaccinated animals. Total and purified lung digest T cells co-cultured with lung macrophages (LMøs) proliferated poorly after PPD stimulation in both non-vaccinated and BCG-vaccinated animals while robust proliferation to PPD was observed when T cells were co-cultured with peritoneal macrophages (PMøs). Macrophages within the lung compartment appear to regulate the response of T cells irrespective of the vaccination status in guinea pigs. Taken together, our results suggest that type I cytokine mRNA expression is not associated with vaccine-induced protection in the low-dose guinea pig model of tuberculosis.
authors.affiliation: Microbial and Molecular Pathogenesis, Texas A&M Health Science Center, College Station, TX 77843-1114, USA. ajeevan@medicine.tamhsc.edu
authors.forename: Amminikutty
authors.initials: A
authors.lastname: Jeevan
authors.forename: Diana Lucia
authors.initials: DL
authors.lastname: Bonilla
authors.forename: David Neil
authors.initials: DN
authors.lastname: McMurray
mesh_terms: D000818:Animals; D001500:BCG Vaccine / Q000276:immunology*; D049109:Cell Proliferation / Q000187:drug effects; D003208:Concanavalin A / Q000494:pharmacology; D004195:Disease Models, Animal; D006168:Guinea Pigs; D007371:Interferon-gamma / Q000235:genetics*; D016753:Interleukin-10 / Q000276:immunology / Q000378:metabolism; D053762:Interleukin-12 Subunit p40 / Q000276:immunology / Q000378:metabolism; D008168:Lung / Q000187:drug effects / Q000276:immunology* / Q000382:microbiology; D016676:Macrophages, Alveolar / Q000276:immunology* / Q000382:microbiology; D017737:Macrophages, Peritoneal / Q000276:immunology / Q000382:microbiology; D008934:Mitogens / Q000494:pharmacology; D009169:Mycobacterium tuberculosis / Q000472:pathogenicity*; D012333:RNA, Messenger / Q000096:biosynthesis; D013154:Spleen / Q000187:drug effects / Q000276:immunology / Q000382:microbiology; D013234:Stem Cells / Q000276:immunology / Q000382:microbiology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000382:microbiology; D014158:Transcription, Genetic; D016212:Transforming Growth Factor beta / Q000276:immunology / Q000378:metabolism; D014373:Tuberculin / Q000494:pharmacology; D014397:Tuberculosis, Pulmonary / Q000276:immunology / Q000517:prevention & control*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics*; D014611:Vaccination
chemical_list: D001500:BCG Vaccine; D053762:Interleukin-12 Subunit p40; D008934:Mitogens; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D014373:Tuberculin; D014409:Tumor Necrosis Factor-alpha; D003208:Concanavalin A; D016753:Interleukin-10; D007371:Interferon-gamma