Project description:The century-old Mycobacterium bovis Bacillus Calmette-Guerin (BCG) remains the only licensed vaccine against tuberculosis (TB). Despite this, there is still a lot to learn about the immune response induced by BCG, both in terms of phenotype and specificity. Here, we investigated the BCG-specific gene expression changes induced in PBMCs and CD4 memory T cells by BCG in individuals pre- and 8m post vaccination. We also determined whether reactivity against a peptide pool defined in individuals with controlled latent TB infection (MTB300), and with peptides homologous to peptides found in BCG, was boosted following BCG vaccination.
Project description:The century-old Mycobacterium bovis Bacillus Calmette-Guerin (BCG) remains the only licensed vaccine against tuberculosis (TB). Despite this, there is still a lot to learn about the immune response induced by BCG, both in terms of phenotype and specificity. Here, we investigated immune responses in adult individuals pre and 8 months post BCG vaccination. We specifically determined changes in gene expression, cell subset composition, DNA methylome, and the TCR repertoire induced in PBMCs and CD4 memory T cells associated with antigen stimulation by either BCG or a Mycobacterium tuberculosis (Mtb)-derived peptide pool. Following BCG vaccination, we observed increased frequencies of CCR6+ CD4 T cells, which includes both Th1* and Th17 subsets, and mucosal associated invariant T cells (MAITs). A large number of immune response genes and pathways were upregulated post BCG vaccination with similar patterns observed in both PBMCs and memory CD4 T cells, thus suggesting a substantial role for CD4 T cells in the cellular response to BCG. These upregulated genes and associated pathways were also reflected in the DNA methylome. We described both qualitative and quantitative changes in the BCG-specific TCR repertoire post vaccination, and importantly found evidence for similar TCR repertoires across different subjects. The immune signatures defined herein can be used to track and further characterize immune responses induced by BCG, and can serve as reference for benchmarking novel vaccination strategies.
Project description:Vaccination against tuberculosis by intradermal Bacillus Calmette-Guérin (BCG) injection saves many lives, supposedly by inducing adaptive immune memory in lymphocytes. Epidemiologically, BCG vaccination is also associated with reduced childhood mortality unrelated to TB, which is attributed to innate immune memory, also termed trained immunity. We recently demonstrated improved protection against tuberculosis infection in highly susceptible rhesus macaques by mucosal BCG vaccination, correlating with a unique local but no peripheral immune profile. Here, we investigated local and peripheral innate immune function after intradermal versus mucosal vaccination with M. bovis BCG or the live attenuated, M. tuberculosis-derived candidate, MTBVAC. The results demonstrate an augmented frequency of trained immunity in monocytes after respiratory mucosal administration of live attenuated mycobacterial vaccines compared to intradermal immunization, with MTBVAC being equally potent as BCG. These results provide further support to strategies for improving TB vaccination and, more broadly, modulating innate immunity via mucosal surfaces.
Project description:To determine the blood transcriptional response to intravenous (IV) BCG vaccination in rhesus macaques and identify correlates of vaccine-mediated protection against Mycobacterium tuberculosis (Mtb) challenge.
Project description:Although BCG has been used for almost 100 years to immunize against Mycobacterium tuberculosis, TB remains a global public health threat. Numerous clinical trials are underway studying novel vaccine candidates and strategies to improve or replace BCG, but vaccine development still lacks a well-defined set of immune correlates to predict vaccine-induced protection against tuberculosis. This study aimed to address this gap by examining transcriptional responses to BCG vaccination in C57BL/6 inbred mice, coupled with protection studies using Diversity Outbred mice. We evaluated relative gene expression in blood obtained from vaccinated mice, because blood is easily accessible and data can be translated to human studies. We first determined that the average peak time after vaccination is 14 days for gene expression of a small subset of immune-related genes in inbred mice. We then performed global transcriptomic analyses using whole blood samples obtained two weeks after mice were vaccinated with BCG. Using comparative bioinformatic analyses and qRT-PCR validation, we developed a working correlate panel of 18 genes that were highly correlated with administration of BCG but not heat-killed BCG. We then tested this gene panel using BCG-vaccinated Diversity Outbred mice and revealed associations between the expression of a subset of genes and disease outcomes after aerosol challenge with M. tuberculosis. These data therefore demonstrate that blood-based transcriptional immune correlates measured within a few weeks after vaccination can be derived to predict protection against M. tuberculosis, even in outbred populations.
Project description:To determine the blood transcriptional response to BCG vaccination administered via different routes in rhesus macaques and identify correlates of vaccine-mediated protection against Mycobacterium tuberculosis (Mtb) challenge.
Project description:Bacille Calmette-Guérin (BCG) vaccination can confer non-specific protection against heterologous pathogens. However, the underlying mechanisms remain mysterious. We used scRNA-seq in this study to identify transcriptional changes in the immune and epithelial cells in the lungs following BCG vaccination in mice
Project description:Bacillus Calmette–Guérin (BCG) vaccination immediately after birth provides overall protection against immune disorders in healthy infants. However, for vulnerable infants such as preterm or low birth weights, delayed BCG vaccination is usually recommended. The mechanism underlying this clinical application remains obscure. Here we reported that BCG vaccination abrogated the transitory appearance of immunosuppressive myeloid cells in neonatal mice, that is myeloid-derived suppressor cells (MDSCs) represented as the important immunoprotection against inflammatory diseases in early life. A combination of single-cell transcriptome, metabolite profiling, and functional analysis revealed that the upregulation of mTOR/HIF1a signaling and the enhanced glycolysis explained the underlying mechanism. Consequently, BCG vaccination significantly exacerbated the severity of necrotizing enterocolitis (NEC), a common clinical emergency primarily affecting preterm or low birth weight infants. Adoptive transfer of MDSCs or pharmalogical inhibition of glycolysis or mTOR signaling efficiently relieved the severity of NEC upon BCG vaccination. These observations suggest that BCG may diminish the protective mechanism of myeloid cells and enhances the susceptibility of NEC in vulnerable neonates.
Project description:In the present study, we applied microarray technology to define a biosignature from the whole genome expression in lung and spleen samples after BCG vaccination and M. bovis infection of BALB/c mice. The aims were two-fold, namely to define biosignatures that could predict vaccine success before challenge, and biomarker patterns that correlated with anamnestic protective responses following exposure to virulent M. bovis. Further, Our aim was to define these markers to be detectable without in vitro antigenic challenge. After BCG vaccination, we defined a specific pulmonary gene expression signature related to the connective tissue development and function network that predicted vaccine success before M. bovis challenge. In addition, a Th17-related cytokine profile was found that correlated with vaccine-induced protective immunity following infection with virulent M. bovis in the lung as well as additional genes that were up-regulated in the spleens of vaccinated animals post-infection that was related to neutrophil biology and inflammation. This study has therefore prioritized both biomarkers predicting vaccination success before challenge and bio-signatures that are associated with protective immune responses that will be useful to evaluate future vaccine candidates. Two groups of 20 mice each were immunised by a single intradermal injection of 2 x 10 to 5 CFU of M. bovis BCG (Vaccinated), or Hanks buffered salt solution (HBSS) (Unvaccinated). Six weeks later 5 mice from each group were euthanized for immunological analyses and the remaining mice from each group were challenged with approx 600 CFU M. bovis via the intranasal route. At days 3 and 14 post challenge five mice per group were euthanized and spleens and lungs harvested.