Project description:Mycobacterium tuberculosis (Mtb) is the leading cause of death from infection worldwide. Intradermal (ID) vaccination with BCG has variable efficacy against pulmonary tuberculosis, the major cause of mortality and disease transmission. Here we show that the route and dose of BCG vaccination alters circulating and lung resident T cells and subsequent protection against Mtb challenge in nonhuman primates (NHP). NHP immunized with BCG by the intravenous (IV) route induced substantially higher antigen-specific CD4 (Th1 or Th17) and CD8 responses in blood, spleen, bronchoalveolar lavage (BAL), and lung lymph nodes compared to the same BCG dose administered by ID or aerosol (AE) routes. Moreover, IV immunization was the only route that induced a high frequency of antigen-specific tissue resident T cells in lung parenchyma. Six months after BCG vaccination, NHP were challenged with virulent Mtb. Strikingly, 9 of 10 NHP that received BCG IV were highly protected, with 6 NHP showing no detectable infection as determined by PET CT imaging, mycobacterial growth, pathology, granuloma formation, or de novo immune responses to Mtb-specific antigens. The finding that BCG IV prevents or significantly limits Mtb infection in NHP has important implications for vaccine development and provides a model for determining immune correlates and mechanisms of protection against TB.
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:After a century of the Bacillus Calmette-Guérin (BCG) vaccine, our understanding of its protection against homologous (Mycobacterium tuberculosis) or heterologous (e.g. influenza virus) infections is still limited. Here we show that systemic (intravenous) BCG vaccination (BCG-iv) provides significant protection against subsequent influenza A virus (IAV) infection in mice. We further demonstrate that the BCG-mediated cross-protection against IAV is largely due to the enrichment of conventional CD4+ αβ effector memory T cells that express high levels of CX3CR1hi in circulation trafficking into the lung parenchyma. Importantly, pulmonary CX3CR1hi T cells limit early viral infection in an antigen-independent manner via potent IFNγ production, which subsequently enhances long-term antimicrobial activity of the innate immune system like alveolar macrophages. Similarly, we uncover a prominent IFNγ signature in which its increased basal production was associated with enhanced BCG-mediated heterologous innate memory responses in BCG-vaccinated humans. These results offer insight into the unknown mechanism by which BCG has persistently displayed broad protection against non-tuberculous infections via a crosstalk between adaptive and innate memory responses.
Project description:Interferons (IFNs) are critical for anti-viral host defence. Type-1 and type-3 IFNs are typically associated with early control of viral replication and promotion of inflammatory immune responses; however, less is known about the role of IFNγ in anti-viral immunity, particularly in the context of SARS-CoV-2. We have previously observed that lung infection with attenuated bacteria M. bovis BCG achieved though intravenous (iv) administration provides strong protection against SARS-CoV-2 (SCV2) infection and disease in two mouse models. Assessment of the pulmonary cytokine milieu revealed that iv BCG induces a robust IFNγ response and low levels of IFNβ. Here we examined the role of ongoing IFNγ responses due to concurrent bacterial infection on SCV2 disease outcomes in two murine models. We report that IFNγ is required for iv BCG induced reduction in pulmonary viral loads and that this outcome is dependent on IFNγ receptor expression by non-hematopoietic cells. Further analysis revealed that BCG infection promotes the upregulation of ISGs with reported anti-viral activity by pneumocytes and bronchial epithelial cells in an IFNγ dependent manner, suggesting a possible mechanism for the observed protection. Finally, we confirmed the importance of IFNγ in these anti-viral effects by demonstrating that the recombinant cytokine itself provides strong protection against SCV2 challenge when administered intranasally. Together, our data show that a pre-established IFNγ response within the lung is protective against SCV2 infection, suggesting that concurrent or recent infections that drive IFNγ may limit the pathogenesis of this virus and supporting possible prophylactic uses of this cytokine in COVID-19 management.
Project description:The alteration of protein expression profile mediated by Bacillus Calmette-Guérin (BCG) treatment remains unclear and is rarely studied. Three paired before BCG(pre-BCG) and during BCG(on-BCG) tissues were collected for proteomicsanalyses to describe the proteomic changes caused by 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:This experiment explored the transcriptional response of human peripheral blood mononuclear cells (PBMC) isolated from BCG-vaccinated individuals following 6 days of in vitro stimulation with 2x10^5 cfu of different Bacillus Calmette-Guérin (BCG) strains or 100 ng/ml Mycobacterium tuberculosis-derived purified protein derivative (PPD). The BCG strains used were BCG Russia (Russian BCG-I sub-strain), BCG Japan (Tokyo 172 sub-strain), BCG Denmark (Danish 1331 sub-strain) & BCG Pasteur.
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:T cell development and selection is orchestrated in the thymus by a specialized niche of diverse stromal populations. By transcriptional single cell sorting, we de novo characterize the entire stromal compartment of the thymus. We identified dozens of cell states within the thymic stroma, with thymic epithelial cells (TEC) showing the highest degree of heterogeneity. Our analysis highlights four major medullary TEC (mTEC I-IV) populations, with distinct molecular functions, epigenetic landscapes and lineage regulators. Specifically, mTEC-IV constitutes a new and highly divergent TEC lineage with molecular characteristics of the gut chemosensory epithelial tuft cells. Mice deficient of Pou2f3, a tuft cells master regulator, resulted in complete and specific depletion of mTEC-IV, without affecting other TEC populations. Overall, our study comprehensively defines all stroma cells in the thymus and identifies a new TEC lineage associated with chemosensory properties that may potentially link the adaptive immune system to environmental and neurological signals.