BCG vaccination-induced emergency granulopoiesis provides rapid protection from neonatal sepsis.
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ABSTRACT:
SUBMITTER: Brook B
PROVIDER: S-EPMC8008103 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Mycobacterium bovis bacille Calmette-Guérin (BCG) is the most widely used live bacterial vaccine. However, limited information is available correlating route and dose of vaccination and induction of specific T cell responses with protection against tuberculosis. We compared efficacy of oral and systemic vaccination and correlated vaccine-induced T cell responses with protection in experimental tuberculosis of mice. After oral and systemic vaccination, we observed profound differences in persistence and dissemination of BCG and frequencies and location of specific IFN-gamma-secreting CD4(+) and CD8(+) T cells. Yet, both vaccination routes caused comparable levels of protection against aerosol challenge with Mycobacterium tuberculosis. Protection correlated best with rapid accumulation of specific CD8(+) T cells in infected tissues of challenged mice. In contrast, specific IFN-gamma production by CD4(+) T cells reflected the load of M. tuberculosis rather than the strength of protection. Our data question the measurement of IFN-gamma secretion by CD4(+) T cells and emphasize the need for new biomarkers for evaluation of tuberculosis vaccine efficacies.
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Project description:Emergency granulopoiesis refers to the increased production of neutrophils in bone marrow and their release into circulation induced by severe infection. Several studies point to a critical role for granulocyte colony-stimulating factor (G-CSF) as the main mediator of emergency granulopoiesis. However, the consequences of G-CSF stimulation on the transcriptome of neutrophils and their precursors have not yet been investigated in humans. Here, we examine the changes in mRNA expression induced by administration of G-CSF in vivo, as a model of emergency granulopoiesis in humans. Blood samples were collected from healthy individuals after five days of G-CSF administration. Neutrophil precursors were sorted into discrete stages of maturation by flow cytometry, and RNA was subjected to microarray analysis. mRNA levels were compared to previously published expression levels in corresponding populations of neutrophil precursors isolated from bone marrow of untreated, healthy individuals. 1110 mRNAs were differentially expressed more than 2-fold throughout terminal granulopoiesis. Major changes were seen in pathways involved in apoptosis, cytokine signaling, and Toll-like receptor pathways. In addition, G-CSF treatment reduced the levels of four out of five measured granule proteins in mature neutrophils including the proantibacterial protein hCAP-18, which was completely deficient in neutrophils from G-CSF-treated donors. These results indicate that multiple biological processes are altered in order to satisfy the increased demand for neutrophils during G-CSF-induced emergency granulopoiesis in humans.
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Project description:Whether the intranasal (i.n.) route of Mycobacterium bovis BCG vaccination provides better protection against pulmonary tuberculosis than subcutaneous (s.c.) vaccination remains an incompletely solved issue. In the present study, we compared both immune responses and protection elicited by single BCG vaccinations via the i.n. or s.c. route in BALB/c mice. While both i.n. and s.c. vaccination triggered comparable levels of primary immune activation in the spleen and draining lymph nodes, i.n. vaccination led to a greater antigen-specific gamma interferon recall response in splenocytes than s.c. vaccination upon secondary respiratory mycobacterial challenge, accompanied by an increased frequency of antigen-specific lymphocytes. There was also a quicker cellular response in the lungs of i.n. vaccinated mice upon mycobacterial challenge. Mice vaccinated i.n. were found to be much better protected, particularly in the lung, than s.c. vaccinated counterparts against pulmonary tuberculosis at both 3 and 6 months postvaccination. These results suggest that the i.n. route of vaccination improves the protective effect of the current BCG vaccine.
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