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.
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.
Jeevan
Amminikutty
A
Microbial and Molecular Pathogenesis, Texas A&M Health Science Center, College Station, TX 77843-1114, USA. ajeevan@medicine.tamhsc.edu
Bonilla
Diana Lucia
DL
McMurray
David Neil
DN
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
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