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:Vaccination with Bacillus Calmette-Guérin (BCG) induces long-term innate immune memory, also called trained immunity, characterized by metabolic and epigenetic changes leading to enhanced responsiveness upon exposure to heterologous pathogens. BCG vaccination was also shown to reduce systemic inflammation. Thus, BCG counteracts two significant immunological changes associated with aging: impaired responsiveness and elevated systemic inflammation. However, if and how BCG impacts other aging-related processes in immune cells, such as telomere shortening, remains unexplored. In this study, we investigated the transcriptional impact of BCG training on telomere maintenance-related genes through RNA sequencing and determined average telomere length from whole blood via RT-qPCR before and three months after BCG vaccination in two independent human cohorts. Trained immunity response was measured by ex-vivo cytokine production induced by a heterologous stimulus three months after vaccination compared to baseline. In addition, we examined the effects of BCG on telomerase activation using an in vitro trained immunity model. In vitro BCG training upregulated processes related to telomere maintenance and telomerase localization. In vivo, we observed shorter telomeres three months after BCG vaccination in both studies. Interestingly, the induction of a trained immunity response by BCG was correlated to the change in telomere length: more telomere shortening was observed in trained immunity non-responder individuals, particularly in males. Higher testosterone concentrations before vaccination were linked to more telomere loss. In vitro, BCG training of human monocytes activated the telomerase enzyme, predominantly in females, an effect that was blocked by exogenous testosterone treatment. Overall, this study reports sex-specific long-term impacts of BCG vaccination on telomerase activity and telomere maintenance. These data add to the arguments that BCG vaccination impacts aging mechanisms, which warrants more investigation.
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:The innate immune system can develop memory-like features, recalling past infections or vaccinations and enabling more efficient responses to future threats, a process known as trained immunity (cite). Trained innate immune cells triggered by various microbial components or vaccines such as Bacille Calmette-Guérin (BCG), can confer broad-spectrum, heterologous (non-specific) protection against diverse pathogens. Subjects were vaccinated in with BCG vaccine and lood samples were obtained immediately before BCG vaccination (day 0) and subsequently on day 14 and day 90 post-vaccination
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