Biology subjects

Divangahi, M.

Publications and source records attributed to Divangahi, M..

7 recordsLinked to original sources

bioRxiv2025

Neonatal BCG Vaccination Engages the Vasculature to Elicit γδ T Cell-Mediated Protection against Tuberculosis

The Bacillus Calmette-Guerin (BCG) vaccine remains the only approved vaccine against tuber-culosis (TB). Although its efficacy against pulmonary TB in adults is limited, BCG provides re-markable protection against miliary TB when administered during infancy. Despite more than 100 million infants worldwide receiving BCG annually, the mechanisms underlying its neonatal protective effects remain poorly defined. Here, we demonstrate that subcutaneous neonatal BCG vaccination (BCG-sc) induces a marked expansion of {gamma}{delta} T cells producing IL-17 and IL-22, which mediated protection against subsequent Mycobacterium tuberculosis (Mtb) experimental infection. A similar expansion of {gamma}{delta} T cells was observed in a longitudinal cohort of infants, from birth to three months of infants followed after intradermal BCG vaccination. Mechanistical-ly, BCG-mediated protection in neonates was linked to its early vascular dissemination through the distinct structure of neonatal skin, resembling the protective effects of intravenous BCG in adults. Moreover, neonatal BCG-sc vaccination generated a distinct BCG-induced microbiome signature, characterized by enrichment of Prevotellaceae, Tannerellaceae, and Bifidobacteriaceae, which was associated with protection. Together, these findings identify {gamma}{delta} T cells as key mediators of early-life BCG-induced immunity and highlight the role of the gut-lung axis in long-term protection against TB from infancy into adulthood.

immunology↗

bioRxiv2024

β-Glucan Reprograms Neutrophils to Induce Disease Tolerance Against Influenza A Virus

ABSTRACTDisease tolerance is an evolutionarily conserved host defence strategy that preserves tissue integrity and physiology without affecting pathogen load. Unlike host resistance, the mechanisms underlying disease tolerance remain poorly understood. In the present study, we investigated whether an adjuvant ({beta}-glucan) can reprogram innate immunity to provide protection against Influenza A virus (IAV) infection. Here we observe that {beta}-glucan treatment reduced the morbidity and mortality against IAV infection, independent of host resistance (viral load). Increased survival of {beta}-glucan treated mice against IAV is associated with the accumulation of neutrophils via RoR{gamma}t+ T cells in the lung tissue. Using gain-and-loss-of-function approaches, we demonstrate that {beta}- glucan reprogrammed neutrophils are essential for promoting disease tolerance, limiting pulmonary tissue damage, and enhancing survival against IAV infection. {beta}-glucan treatment promotes granulopoiesis in a type 1 interferon-dependent manner that leads to the generation of a unique subset of neutrophils, which are less mature with higher mitochondrial mass utilizing mitochondrial oxidative (OXPHOS) metabolism. Collectively, our data indicate that {beta}-glucan reprograms hematopoietic stem cells (HSCs) to generate neutrophils with a novel "regulatory" function, which is required for promoting disease tolerance and maintaining lung tissue integrity against viral infection.

immunology↗

bioRxiv2024

β-glucan reprograms alveolar macrophages via neutrophil/IFNγ axis to promote lung injury

Alveolar macrophages (AMs) reside in the lower airways and play a crucial role in lung health and response to sterile inflammation and infections. AMs possess remarkable adaptability to different environmental challenges that can persist through their memory capacity (trained immunity). {beta}-glucan has been characterized as a potent inducer of central trained immunity by reprogramming hematopoietic stem cells (HSCs) in the bone marrow. In the present study, we show that systemic administration of {beta}-glucan induces peripheral trained immunity by reprogramming alveolar macrophages (AMs) in the lungs, in a Dectin1-independent manner. We furthermore demonstrate that AM reprogramming at both the transcriptional and metabolic levels exacerbate lung injury following bacterial (LPS) or viral (polyI:C) challenges via a neutrophil/IFN-{gamma} dependent manner. These findings identify an additional facet of {beta}-glucan in trained immunity involving AM reprogramming and shed light on the potential detrimental effects of trained immunity.

immunology↗

bioRxiv2024

Microbial cancer immunotherapy reprograms hematopoietic stem cells to enhance anti-tumor immunity

Mycobacterium bovis BCG is the vaccine against tuberculosis and an immunotherapy for bladder cancer. When administered intravenously, BCG reprograms bone marrow hematopoietic stem and progenitor cells (HSPCs), leading to heterologous protection against infections. Whether HSPC-reprogramming contributes to the anti-tumor effects of BCG administered into the bladder is unknown. We demonstrate that BCG administered in the bladder in both mice and humans reprograms HSPCs to amplify myelopoiesis and functionally enhance myeloid cell antigen presentation pathways. Reconstitution of naive mice with HSPCs from bladder BCG-treated mice enhances anti-tumor immunity and tumor control, increases intratumor dendritic cell infiltration, reprograms pro-tumorigenic neutrophils, and synergizes with checkpoint blockade. We conclude that bladder BCG acts systemically, reprogramming HSPC-encoded innate immunity, highlighting the broad potential of modulating HSPC phenotypes to improve tumor immunity. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=199 HEIGHT=200 SRC="FIGDIR/small/586166v2_ufig1.gif" ALT="Figure 1"> View larger version (73K): org.highwire.dtl.DTLVardef@16b81a7org.highwire.dtl.DTLVardef@10cfebforg.highwire.dtl.DTLVardef@28bf93org.highwire.dtl.DTLVardef@1396184_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2023

BCG vaccination impacts the epigenetic landscape of progenitor cells in human bone marrow

While the Bacille-Calmette-Guerin (BCG) vaccine is used to prevent tuberculosis, it also offers protection against a diverse range of non-mycobacterial infections. However, the underlying protective mechanisms in humans are not yet fully understood. Here, we surveyed at single-cell resolution the gene expression and chromatin landscape of human bone marrow, aspirated before and 90 days after BCG vaccination or placebo administration. We show that BCG vaccination significantly alters both the gene expression and epigenetic profiles of human hematopoietic stem and progenitor cells (HSPCs). Changes in gene expression occur primarily on the most uncommitted stem cells and are reflective of a persistent myeloid bias. In contrast, BCG-induced changes in chromatin accessibility are most prevalent within differentiated progenitor cells at sites influenced by Kruppel-like factor (KLF)/SP and EGR transcription factors (TFs). These TFs are also activated in the most uncommitted stem cells, indicating that activated TFs, which drive persistent changes in HSC gene expression, likely also drive chromatin dynamics appearing within downstream progenitor cells. This perspective contests the prevailing notion that epigenetic modifications linked to innate immune memory transfer directly from stem cells to their differentiated derivatives. Finally, we show that alterations in gene expression and chromatin accessibility in HSPCs due to BCG vaccination were highly correlated (r>0.8) with the IL-1{beta} secretion capacity of paired PBMCs upon secondary immune challenge. Overall, our findings shed light on BCG vaccinations profound and lasting effects on HSPCs and its influence on innate immune responses.

immunology↗

bioRxiv2021

Lung epithelial signaling mediates early vaccine-induced CD4+ T cell activation and Mtb control

Tuberculosis (TB) is one of the leading causes of death due to a single infectious agent. The development of a TB vaccine that induces durable and effective immunity to Mycobacterium tuberculosis (Mtb) infection is urgently needed. Early and superior Mtb control can be induced in M. bovis Bacillus Calmette-Guerin (BCG) vaccinated hosts when the innate immune response is targeted to generate effective vaccine-induced immunity. In the present study, we show that innate activation of DCs is critical for mucosal localization of clonally activated vaccine-induced CD4+ T cells in the lung, and superior early Mtb control. In addition, our study reveals that Th1/Th17 cytokine axis play an important role in superior vaccine induced immunity. Our studies also show that activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF{kappa}{beta}) pathway in lung epithelial cells is critical for the mucosal localization of activated vaccine-induced CD4+ T cells for rapid Mtb control. Thus, our study provides novel insights into the immune mechanisms that can overcome TB vaccine bottlenecks and provide early rapid Mtb control. ImportanceTuberculosis is a leading cause of death due to single infectious agent accounting 1.4 million deaths each year. The only licensed vaccine BCG is not effective due to variable efficacy. In our study, we determined the early immune events necessary for achieving complete protection in BCG vaccinated host. Our study reveals that innate activation of DCs can mediate superior and early Mtb control in BCG vaccinated host through lung epithelial cell signaling and localization of clonal activated, Mtb antigen specific, cytokine producing CD4+ T cells within the lung parenchyma and airways. Thus, our study provides novel insights into the immune mechanisms that can overcome TB vaccine bottlenecks and provide early rapid Mtb control.

immunology↗

bioRxiv2021

Mitochondrial cyclophilin D promotes disease tolerance by licensing NK cell development and IL-22 production against influenza virus

Immunity to infectious disease involves a combination of host resistance, which eliminates the pathogen, and disease tolerance, which limits tissue damage. While the severity of most pulmonary viral infections, including influenza A virus (IAV), is linked to excessive inflammation, our mechanistic understanding of this observation remains largely unknown. Here we show that mitochondrial cyclophilin D (CypD) protects against IAV infection via disease tolerance. Mice deficient in CypD (CypD-/- mice) are significantly more susceptible to IAV infection despite comparable antiviral immunity. Instead, this susceptibility resulted from damage to the lung epithelial barrier caused by a significant reduction of IL-22 production by conventional NK cells in IAV-infected CypD-/- mice. Transcriptomic and functional data revealed that the compromised IL-22 production by NK cells resulted from dysregulated lymphopoiesis, stemming from increased cell death in NK cell progenitors, as well as the generation of immature NK cells that exhibited altered mitochondrial metabolism. Importantly, following IAV infection, administration of recombinant IL-22 abrogated pulmonary damage and enhanced survival of CypD-/- mice. Collectively, these results demonstrate a key role for CypD in NK cell-mediated disease tolerance.

immunology↗