Shaun McColl

In vivo dual RNA-seq reveals that neutrophil recruitment underlies differential tissue tropism of Streptococcus pneumoniae

Publisher: Springer Science and Business Media LLC

Date: 05-06-2020

DOI: 10.1038/S42003-020-1018-X

Abstract: Streptococcus pneumoniae is a genetically erse human-adapted pathogen commonly carried asymptomatically in the nasopharynx. We have recently shown that a single nucleotide polymorphism (SNP) in the raffinose pathway regulatory gene rafR accounts for a difference in the capacity of clonally-related strains to cause localised versus systemic infection. Using dual RNA-seq, we show that this SNP affects expression of bacterial genes encoding multiple sugar transporters, and fine-tunes carbohydrate metabolism, along with extensive rewiring of host transcriptional responses to infection, particularly expression of genes encoding cytokine and chemokine ligands and receptors. The data predict a crucial role for differential neutrophil recruitment (confirmed by in vivo neutrophil depletion and IL-17 neutralization) indicating that early detection of bacteria by the host in the lung environment is crucial for effective clearance. Thus, dual RNA-seq provides a powerful tool for understanding complex host-pathogen interactions and reveals how a single bacterial SNP can drive differential disease outcomes.

CD4⁺ T cell immunity to Salmonella is transient in the circulation

Publisher: Public Library of Science (PLoS)

Date: 25-10-2021

DOI: 10.1371/JOURNAL.PPAT.1010004

Abstract: While Salmonella enterica is seen as an archetypal facultative intracellular bacterial pathogen where protection is mediated by CD4 + T cells, identifying circulating protective cells has proved very difficult, inhibiting steps to identify key antigen specificities. Exploiting a mouse model of vaccination, we show that the spleens of C57BL/6 mice vaccinated with live-attenuated Salmonella serovar Typhimurium ( S . Typhimurium) strains carried a pool of IFN-γ + CD4 + T cells that could adoptively transfer protection, but only transiently. Circulating Salmonella -reactive CD4 + T cells expressed the liver-homing chemokine receptor CXCR6, accumulated over time in the liver and assumed phenotypic characteristics associated with tissue-associated T cells. Liver memory CD4 + T cells showed TCR selection bias and their accumulation in the liver could be inhibited by blocking CXCL16. These data showed that the circulation of CD4 + T cells mediating immunity to Salmonella is limited to a brief window after which Salmonella -specific CD4 + T cells migrate to peripheral tissues. Our observations highlight the importance of triggering tissue-specific immunity against systemic infections.

Direct interaction of whole-inactivated influenza A and pneumococcal vaccines enhances influenza-specific immunity

Publisher: Springer Science and Business Media LLC

Date: 20-05-2019

DOI: 10.1038/S41564-019-0443-4

Abstract: The upper respiratory tract is continuously exposed to a vast array of potentially pathogenic viruses and bacteria. Influenza A virus (IAV) has particular synergism with the commensal bacterium Streptococcus pneumoniae in this niche, and co-infection exacerbates pathogenicity and causes significant mortality. However, it is not known whether this synergism is associated with a direct interaction between the two pathogens. We have previously reported that co-administration of a whole-inactivated IAV vaccine (γ-Flu) with a whole-inactivated pneumococcal vaccine (γ-PN) enhances pneumococcal-specific responses. In this study, we show that mucosal co-administration of γ-Flu and γ-PN similarly augments IAV-specific immunity, particularly tissue-resident memory cell responses in the lung. In addition, our in vitro analysis revealed that S. pneumoniae directly interacts with both γ-Flu and with live IAV, facilitating increased uptake by macrophages as well as increased infection of epithelial cells by IAV. These observations provide an additional explanation for the synergistic pathogenicity of IAV and S. pneumoniae, as well as heralding the prospect of exploiting the phenomenon to develop better vaccine strategies for both pathogens.

CXCR5+CD8+ T Cells Shape Antibody Responses In Vivo Following Protein Immunisation and Peripheral Viral Infection

Publisher: Frontiers Media SA

Date: 13-07-2021

DOI: 10.3389/FIMMU.2021.626199

Abstract: Crosstalk between T and B cells is crucial for generating high-affinity, class-switched antibody responses. The roles of CD4 + T cells in this process have been well-characterised. In contrast, regulation of antibody responses by CD8 + T cells is significantly less defined. CD8 + T cells are principally recognised for eliciting cytotoxic responses in peripheral tissues and forming protective memory. However, recent findings have identified a novel population of effector CD8 + T cells that co-opt a differentiation program characteristic of CD4 + T follicular helper (Tfh) cells, upregulate the chemokine receptor CXCR5 and localise to B cell follicles. While it has been shown that CXCR5 + CD8 + T cells mediate the removal of viral reservoirs in the context of follicular-trophic viral infections and maintain the response to chronic insults by virtue of progenitor/stem-like properties, it is not known if CXCR5 + CD8 + T cells arise during acute peripheral challenges in the absence of follicular infection and whether they influence B cell responses in vivo in these settings. Using the ovalbumin-specific T cell receptor transgenic (OT-I) system in an adoptive transfer-immunisation/infection model, this study demonstrates that CXCR5 + CD8 + T cells arise in response to protein immunisation and peripheral viral infection, displaying a follicular-homing phenotype, expression of cell surface molecules associated with Tfh cells and limited cytotoxic potential. Furthermore, studies assessing the B cell response in the presence of OT-I or Cxcr5 -/- OT-I cells revealed that CXCR5 + CD8 + T cells shape the antibody response to protein immunisation and peripheral viral infection, promoting class switching to IgG2c in responding B cells. Overall, the results highlight a novel contribution of CD8 + T cells to antibody responses, expanding the functionality of the adaptive immune system.

The Emerging Complexity of γδT17 Cells.

Publisher: Frontiers Media SA

Date: 20-04-2018

DOI: 10.3389/FIMMU.2018.00796

Large deletions induced by Cas9 cleavage

Publisher: Springer Science and Business Media LLC

Date: 08-2018

DOI: 10.1038/S41586-018-0380-Z

Enhanced safety and immunogenicity of a pneumococcal surface antigen A mutant whole‐cell inactivated pneumococcal vaccine

Publisher: Wiley

Date: 23-05-2019

DOI: 10.1111/IMCB.12257

Abstract: Existing capsular polysaccharide-based vaccines against pneumococcal disease are highly effective against vaccine-included serotypes, but they are unable to combat serotype replacement. We have developed a novel pneumococcal vaccine that confers serotype-independent protection, and could therefore constitute a "universal" vaccine formulation. This preparation is comprised of whole un-encapsulated pneumococci inactivated with gamma irradiation (γ-PN), and we have previously reported induction of cross-reactive immunity after nonadjuvanted intranasal vaccination. To further enhance vaccine immunogenicity and safety, we modified the pneumococcal vaccine strain to induce a stressed state during growth. Specifically, the substrate binding component of the psaBCA operon for manganese import was mutated to create a pneumococcal surface antigen A (psaA) defective vaccine strain. psaA mutation severely attenuated the growth of the vaccine strain in vitro without negatively affecting pneumococcal morphology, thereby enhancing vaccine safety. In addition, antibodies raised against vaccine preparations based on the modified strain [γ-PN(ΔPsaA)] showed more ersified reactivity to wild-type pneumococcal challenge strains compared to those induced by the original formulation. The modified vaccine also induced comparable protective T

Eomesodermin promotes the development of type 1 regulatory T (T _R 1) cells

Publisher: American Association for the Advancement of Science (AAAS)

Date: 21-04-2017

DOI: 10.1126/SCIIMMUNOL.AAH7152

Abstract: T R 1 cells are the major regulatory population generated after allogeneic bone marrow transplantation.

Raw N-glycan mass spectrometry imaging data on formalin-fixed mouse kidney

Publisher: Elsevier BV

Date: 12-2018

DOI: 10.1016/J.DIB.2018.08.186

ACKR4 restrains antitumor immunity by regulating CCL21

Publisher: Rockefeller University Press

Date: 14-04-2020

DOI: 10.1084/JEM.20190634

Abstract: Current immunotherapies involving CD8+ T cell responses show remarkable promise, but their efficacy in many solid tumors is limited, in part due to the low frequency of tumor-specific T cells in the tumor microenvironment (TME). Here, we identified a role for host atypical chemokine receptor 4 (ACKR4) in controlling intratumor T cell accumulation and activation. In the absence of ACKR4, an increase in intratumor CD8+ T cells inhibited tumor growth, and nonhematopoietic ACKR4 expression was critical. We show that ACKR4 inhibited CD103+ dendritic cell retention in tumors through regulation of the intratumor abundance of CCL21. In addition, preclinical studies indicate that ACKR4 and CCL21 are potential therapeutic targets to enhance responsiveness to immune checkpoint blockade or T cell costimulation.

A divergent transcriptional landscape underpins the development and functional branching of MAIT cells

Publisher: American Association for the Advancement of Science (AAAS)

Date: 11-2019

DOI: 10.1126/SCIIMMUNOL.AAY6039

Abstract: Characterizing MAIT cell development led to the identification of key regulators that specify MAIT cell fate in the thymus.

Atypical chemokine receptor 4 shapes activated B cell fate

Publisher: Rockefeller University Press

Date: 31-01-2018

DOI: 10.1084/JEM.20171067

Abstract: Activated B cells can initially differentiate into three functionally distinct fates—early plasmablasts (PBs), germinal center (GC) B cells, or early memory B cells—by mechanisms that remain poorly understood. Here, we identify atypical chemokine receptor 4 (ACKR4), a decoy receptor that binds and degrades CCR7 ligands CCL19/CCL21, as a regulator of early activated B cell differentiation. By restricting initial access to splenic interfollicular zones (IFZs), ACKR4 limits the early proliferation of activated B cells, reducing the numbers available for subsequent differentiation. Consequently, ACKR4 deficiency enhanced early PB and GC B cell responses in a CCL19/CCL21-dependent and B cell–intrinsic manner. Conversely, aberrant localization of ACKR4-deficient activated B cells to the IFZ was associated with their preferential commitment to the early PB linage. Our results reveal a regulatory mechanism of B cell trafficking via an atypical chemokine receptor that shapes activated B cell fate.

Chemokine-Driven Migration of Pro-Inflammatory CD4⁺ T Cells in CNS Autoimmune Disease

Publisher: Frontiers Media SA

Date: 16-02-2022

DOI: 10.3389/FIMMU.2022.817473

Abstract: Pro-inflammatory CD4 + T helper (Th) cells drive the pathogenesis of many autoimmune conditions. Recent advances have modified views of the phenotype of pro-inflammatory Th cells in autoimmunity, extending the breadth of known Th cell subsets that operate as drivers of these responses. Heterogeneity and plasticity within Th1 and Th17 cells, and the discovery of subsets of Th cells dedicated to production of other pro-inflammatory cytokines such as GM-CSF have led to these advances. Here, we review recent progress in this area and focus specifically upon evidence for chemokine receptors that drive recruitment of these various pro-inflammatory Th cell subsets to sites of autoimmune inflammation in the CNS. We discuss expression of specific chemokine receptors by subsets of pro-inflammatory Th cells and highlight which receptors may be tractable targets of therapeutic interventions to limit pathogenic Th cell recruitment in autoimmunity.

Scavenging of soluble and immobilized CCL21 by ACKR4 regulates peripheral dendritic cell emigration

Publisher: Proceedings of the National Academy of Sciences

Date: 19-04-2021

DOI: 10.1073/PNAS.2025763118

Abstract: The immune system relies on coordinated interactions between motile cells guided by molecules known as chemokines. However, processes that control chemokine distribution in complex in vivo microenvironments are poorly understood. Dendritic cells in barrier tissues require the chemokine CCL21 to enter lymphatic vessels during tissue egress. Here, we demonstrate that ACKR4 shapes CCL21 distribution in barrier tissues and prevents leakage of CCL21 from the tissue. Without ACKR4, extracellular CCL21 gradients in barrier sites are saturated and nonfunctional, DCs cannot home directly to lymphatic vessels, and excess soluble CCL21 from peripheral tissues pollutes lymph nodes. The results increase understanding of regulation of dendritic cell egress and chemokine distribution in vivo and raise new questions regarding the function of solubilized CCL21.

In Vivo Dual RNA-Seq Analysis Reveals the Basis for Differential Tissue Tropism of Clinical Isolates of Streptococcus pneumoniae

Publisher: Cold Spring Harbor Laboratory

Date: 03-12-2019

DOI: 10.1101/862755

Abstract: Streptococcus pneumoniae is a genetically erse human-adapted pathogen commonly carried asymptomatically in the nasopharynx. We have recently shown that a single nucleotide polymorphism (SNP) in the raffinose pathway regulatory gene rafR accounts for a significant difference in the capacity of clonally-related strains to cause localised versus systemic infection. Here we have used dual RNA-seq to show that this SNP extensively impacts both bacterial and host transcriptomes in infected lungs. It affects expression of bacterial genes encoding multiple sugar transporters, and fine-tunes carbohydrate metabolism, along with extensive rewiring of host transcriptional responses to infection, particularly expression of genes encoding cytokine and chemokine ligands and receptors. The dual RNA-seq data predicted a crucial role for differential neutrophil recruitment in the distinct virulence profiles of the infecting strains and single cell analysis revealed that while reduced expression of the RafR regulon driven by a single rafR SNP provides a clear advantage for pneumococci to colonize the ear, in the lung it leads to massive recruitment of neutrophils and bacterial clearance. Importantly, the observed disease outcomes were confirmed by in vivo neutrophil depletion showing that early detection of bacteria by the host in the lung environment is crucial for effective clearance. Thus, dual RNA-seq provides a powerful tool for understanding complex host-pathogen interactions and revealed how a single bacterial SNP can drive differential disease outcomes.

Dietary zinc and the control of Streptococcus pneumoniae infection

Publisher: Public Library of Science (PLoS)

Date: 22-08-2019

DOI: 10.1371/JOURNAL.PPAT.1007957

Discovery Projects - Grant ID: DP1095263

Start Date: 2010

End Date: 12-2013

Amount: $330,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0989374

Start Date: 2009

End Date: 12-2009

Amount: $550,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0347358

Start Date: 2003

End Date: 12-2004

Amount: $478,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0561115

Start Date: 2005

End Date: 12-2006

Amount: $474,500.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE170100241

Start Date: 07-2017

End Date: 06-2018

Amount: $480,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP110100693

Start Date: 09-2011

End Date: 12-2013

Amount: $180,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0453839

Start Date: 2004

End Date: 12-2004

Amount: $386,892.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0990788

Start Date: 02-2010

End Date: 07-2012

Amount: $375,000.00

Funder: Australian Research Council