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:Besides centrally induced innate immune memory/trained immunity in the bone marrow/peripheral blood by parenteral vaccination or infection, recently emerging evidence suggests that the barrier mucosal tissue-resident innate immune memory may develop via a local inflammatory pathway following mucosal immunologic exposure. However, it remains unclear whether the mucosal-resident innate immune memory may result from integrating distally generated immunological signals following parenteral vaccination/infection. We show here that subcutaneous Bacillus Calmette-Guérin (BCG) vaccination is able to induce memory alveolar macrophages (AM) and trained immunity at the respiratory barrier mucosa. Although parenteral BCG vaccine can centrally train bone marrow progenitors and circulating monocytes, induction of memory AM is entirely independent of circulating monocytes. Rather, parenteral BCG vaccination, via distal mycobacterial dissemination, causes a time-dependent alteration in gut microbiome, barrier function and microbial metabolites including short-chain fatty acids, and subsequently the changes in circulating and lung tissue metabolites, leading to induction of tissue-resident memory macrophages and trained innate immunity in the lung. Our study thus reveals a novel gut microbiota-mediated pathway for innate immune memory development at distal barrier mucosal tissues. Our findings have far-reaching implications in developing next-generation parenteral vaccine strategies against respiratory pathogens such as M.tb.
Project description:Besides centrally induced innate immune memory/trained immunity in the bone marrow/peripheral blood by parenteral vaccination or infection, recently emerging evidence suggests that the barrier mucosal tissue-resident innate immune memory may develop via a local inflammatory pathway following mucosal immunologic exposure. However, it remains unclear whether the mucosal-resident innate immune memory may result from integrating distally generated immunological signals following parenteral vaccination/infection. We show here that subcutaneous Bacillus Calmette-Guérin (BCG) vaccination is able to induce memory alveolar macrophages (AM) and trained immunity at the respiratory barrier mucosa. Although parenteral BCG vaccine can centrally train bone marrow progenitors and circulating monocytes, induction of memory AM is entirely independent of circulating monocytes. Rather, parenteral BCG vaccination, via distal mycobacterial dissemination, causes a time-dependent alteration in gut microbiome, barrier function and microbial metabolites including short-chain fatty acids, and subsequently the changes in circulating and lung tissue metabolites, leading to induction of tissue-resident memory macrophages and trained innate immunity in the lung. Our study thus reveals a novel gut microbiota-mediated pathway for innate immune memory development at distal barrier mucosal tissues. Our findings have far-reaching implications in developing next-generation parenteral vaccine strategies against respiratory pathogens such as M.tb.
Project description:Bacillus Calmette-Guérin (BCG) vaccine is one of the most widely-used vaccines worldwide. In addition to protection against tuberculosis, BCG confers a degree of non-specific protection against other infections by enhancing secondary immune responses to heterologous pathogens, an effect termed trained immunity. To better understand BCG-induced immune reprogramming, we performed single-cell transcriptomic measurements before and after BCG vaccination using secondary immune stimulation with bacterial lipopolysaccharide (LPS). We find that BCG vaccination reduces systemic inflammation, and we identify 75 genes with an altered response to LPS, including several inflammatory mediators such as CCL3 and CCL4 which have a heightened response. Co-expression analysis reveals gene modules containing these cytokines lose coordination after BCG vaccination. Others have increased coordination, including several humanin nuclear isoforms which we confirmed induce trained immunity in vitro. Our results link in vivo BCG administration to single cell transcriptomic changes, validated in human genetics experiments, and highlight new genes which may be responsible for the non-specific protective effects of BCG.
Project description:Induction of trained immunity by human Bacille-Calmette-Guérin (BCG) vaccination is implicated in the beneficial heterologous effects of the vaccine, but the underlying mechanisms remain elusive. We performed global transcriptome analysis of sorted progenitors from bone marrow before (D0) and 90 days after vaccination (D90). BCG vaccination induced transcriptomic myeloid priming of the hematopoietic stem and progenitor cell (HSPC) compartment marked by the upregulation of myeloid and granulocytic pathways alongside the induction of transcription factors connected to myeloid cell function, namely Hepatocyte Nuclear Factors (HNF). These findings are corroborated by higher granulocyte numbers in BCG-vaccinated infants, HNF1-related SNP variants correlating with immune training and elevated serum levels of the HNF1 target gene SERPINA1. Taken together, we reveal a transcriptomic reprograming of HSPCs and peripheral monocytes as a trait of in vivo BCG-induced trained immunity.
Project description:Induction of trained immunity by human Bacille-Calmette-Guérin (BCG) vaccination is implicated in the beneficial heterologous effects of the vaccine, but the underlying mechanisms remain elusive. We performed global transcriptome analysis of sorted progenitors from bone marrow before (D0) and 90 days after vaccination (D90). BCG vaccination induced transcriptomic myeloid priming of the hematopoietic stem and progenitor cell (HSPC) compartment marked by the upregulation of myeloid and granulocytic pathways alongside the induction of transcription factors connected to myeloid cell function, namely Hepatocyte Nuclear Factors (HNF). These findings are corroborated by higher granulocyte numbers in BCG-vaccinated infants, HNF1-related SNP variants correlating with immune training and elevated serum levels of the HNF1 target gene SERPINA1. Taken together, we reveal a transcriptomic reprograming of HSPCs and peripheral monocytes as a trait of in vivo BCG-induced trained immunity.
Project description:Induction of trained immunity by human Bacille-Calmette-Guérin (BCG) vaccination is implicated in the beneficial heterologous effects of the vaccine, but the underlying mechanisms remain elusive. We performed global transcriptome analysis of sorted progenitors from bone marrow before (D0) and 90 days after vaccination (D90). BCG vaccination induced transcriptomic myeloid priming of the hematopoietic stem and progenitor cell (HSPC) compartment marked by the upregulation of myeloid and granulocytic pathways alongside the induction of transcription factors connected to myeloid cell function, namely Hepatocyte Nuclear Factors (HNF). These findings are corroborated by higher granulocyte numbers in BCG-vaccinated infants, HNF1-related SNP variants correlating with immune training and elevated serum levels of the HNF1 target gene SERPINA1. Taken together, we reveal a transcriptomic reprograming of HSPCs and peripheral monocytes as a trait of in vivo BCG-induced trained immunity.
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:Immune responses are tightly regulated, yet highly variable between individuals. To investigate human population variation of trained immunity, we immunized healthy individuals with Bacillus Calmette-Guérin (BCG). This live attenuated vaccine induces not only an adaptive immune response against tuberculosis, but also triggers innate immune activation and memory. We established personal immune profiles and chromatin accessibility maps over a time course of BCG vaccination in 323 individuals. This large resource uncovered genetic and epigenetic predictors of baseline immunity and BCG vaccine response. We found that BCG vaccination enhances the innate immune response only in individuals with dormant immune states at baseline, suggesting that exogeneous induction of trained immunity is not a universal booster of innate immunity, but specifically elevates weak innate immune responses. This study advances our understanding of BCG’s heterologous immune-stimulatory effects and trained immunity in humans. Moreover, our results highlight the value of epigenetic cell states as an “endophenotype” that connects immune function with genotype and the environment.