Biology subjects

MacLeod, M. K.

Publications and source records attributed to MacLeod, M. K..

8 recordsLinked to original sources

bioRxiv2025

Inflammatory chemokine receptors CCR1, CCR2, CCR3 and CCR5 are essential for an optimal T cell response to influenza.

Inflammatory chemokine receptors CCR1/2/3/5 (iCCRs) play an important role in the recruitment of immune cells involved in innate immune functions and orchestrating the adaptive immune response. Here we utilise an influenza A virus (IAV) challenge to investigate the combinatorial roles of the iCCRs in the anti-IAV immune response. We did not observe any gross differences in infection-driven pathology in the absence of iCCRs. Despite iCCR deletion resulting in decreased migration of monocytes, migratory macrophages and B cells to lungs during acute IAV infection, no differences in dendritic cell numbers were observed. Whilst the total number of T cells was similar in lungs of iCCR-deficient mice, the number of IAV-specific CD4 but not CD8 T cells in the lung was strongly reduced in the absence of iCCRs. Furthermore, fewer CD4, but not CD8, T cells produced IFN-{gamma}. This CD4 T cell phenotype persisted into the memory stage of infection, with fewer IAV-specific and IFN-{gamma}+ CD4 but not CD8 T cells at 29 days post infection. In conclusion, despite having no impact on dendritic cell migration between the lung and the draining lymph node, iCCR deletion is associated with an altered CD4 T cell response to IAV infection.

immunology↗

bioRxiv2024

Lung structural cell dynamics are altered by influenza virus infection experience leading to rapid immune protection following viral re-challenge

Lung structural cells, including epithelial cells and fibroblasts, form barriers against pathogens and trigger immune responses following infections such as influenza A virus. This response leads to the recruitment of innate and adaptive immune cells required for viral clearance. Some of these recruited cells remain within the lung following infection and contribute to enhanced viral control following subsequent infections. There is growing evidence that structural cells can also display long-term changes following infection or insults. Here we investigate long-term changes to mouse lung epithelial cells, fibroblasts, and endothelial cells following influenza virus infection and find that all three cell types maintain an imprint of the infection, particularly in genes associated with communication with T cells. Lung epithelial cells from IAV-infected mice display functional changes by more rapidly controlling influenza virus than cells from naive animals. This rapid anti-viral response and increased expression of molecules required to communicate with T cells demonstrates sustained and enhanced functions following infection. These data suggest lung structural cells could be effective targets for vaccines to boost durable protective immunity. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=135 SRC="FIGDIR/small/604410v5_ufig1.gif" ALT="Figure 1"> View larger version (55K): org.highwire.dtl.DTLVardef@2774e0org.highwire.dtl.DTLVardef@6a39e6org.highwire.dtl.DTLVardef@1ff5863org.highwire.dtl.DTLVardef@103df12_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LILung epithelial cells, fibroblasts, and blood endothelial cells maintain an inflammatory imprint of influenza A virus (IAV) infection for at least 40 days post-infection. C_LIO_LIIn vivo re-infection leads to a more spatially restricted anti-viral response compared to primary IAV-infected animals. C_LIO_LIT cells are not required for enhanced viral control early after re-infection in vivo C_LIO_LIEx vivo lung epithelial cells from IAV-infected mice more rapidly control IAV than cells from naive animals in the absence of immune cells. C_LI

immunology↗

bioRxiv2023

Lung influenza virus specific memory CD4 T cell location and optimal cytokine production are dependent on interactions with lung antigen-presenting cells

Influenza A virus (IAV) infection leads to the formation of mucosal memory CD4 T cells that can protect the host. An in-depth understanding of the signals that shape memory cell development is required for more effective vaccine design. We have examined the formation of memory CD4 T cells in the lung following IAV infection of mice, characterising changes to the lung landscape and immune cell composition. IAV-specific CD4 T cells were found throughout the lung at both primary and memory time points. These cells were found near lung airways and in close contact with a range of immune cells including macrophages, dendritic cells, and B cells. Interactions between lung IAV-specific CD4 T cells and MHCII+ cells during the primary immune response were important in shaping the subsequent memory pool. Treatment with an anti-MHCII blocking antibody increased the proportion of memory CD4 T cells found at lung airways but reduced interferon-g expression by IAV-specific immunodominant memory CD4 T cells. The immunodominant CD4 T cells expressed higher levels of PD1 than other IAV-specific CD4 T cells and PD1+ memory CD4 T cells were located further away from MHCII+ cells than their PD1-negative counterparts. This distinction in location was lost in mice treated with anti-MHCII antibody. These data suggest that sustained antigen presentation in the lung impacts on the formation of memory CD4 T cells by regulating their cytokine production and location.

immunology↗

bioRxiv2023

Triphasic production of IFNγ by innate and adaptive lymphocytes following influenza A virus infection

Interferon gamma (IFN{gamma}) is a potent antiviral cytokine that can be produced by many innate and adaptive immune cells during infection. Currently, our understanding of which cells produce IFN{gamma} and where they are located at different stages of an infection are limited. We have used reporter mice to investigate in vivo expression of IFN{gamma} in the lung and secondary lymphoid organs during and following influenza A virus (IAV) infection. We observed a triphasic production of IFN{gamma} expression. Unconventional T cells and innate lymphoid cells, particularly NK cells, were the dominant producers of early IFN{gamma}, while CD4 and CD8 T cells were the main producers by day 10 post-infection. Following viral clearance, some memory CD4 and CD8 T cells continued to produce IFN{gamma} in the lungs and draining lymph node. Interestingly, IFN{gamma} production by lymph node Natural Killer (NK), NKT and innate lymphoid 1 cells also continued to be above naive levels, suggesting memory-like phenotypes for these cells. Analysis of the localisation of IFN{gamma}+ memory CD4 and CD8 T cells demonstrated that cytokine+ T cells were located near airways and in the lung parenchyma. Following a second IAV challenge, lung IAV specific CD8 T cells rapidly increased their expression of IFN{gamma} while CD4 T cells in the draining lymph node increased their IFN{gamma} response. Together, these data suggest that IFN{gamma} production fluctuates based on cellular source and location, both of which could impact subsequent immune responses.

immunology↗

bioRxiv2022

Enhanced survival and low proliferation marks multifunctional virus specific memory CD4 T cells

Cytokine production by memory T cells is a key mechanism of T cell mediated protection. However, we have a limited understanding of the survival and secondary responses of memory T cells with cytokine producing capacities. We interrogate antigen-specific CD4 T cells using a mouse influenza A virus infection model. CD4 T cells with the capacity to produce cytokines survive better than non-cytokine+ cells, displaying a low fold contraction and expressing high levels of pro-survival molecules, CD127 and Bcl2. Transcriptomic analysis reveals a heterogenous population of memory CD4 T cells with three clusters of cytokine+ cells. These clusters match flow cytometry data revealing an enhanced survival signature in cells capable of producing multiple cytokines. These multifunctional cells are, however, less likely to proliferate during and following primary and secondary infections. Despite this, multifunctional memory T cells form a substantial fraction of the secondary memory pool, indicating that survival rather than proliferation may dictate which populations survive within the memory pool. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=86 SRC="FIGDIR/small/520219v3_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@93e62forg.highwire.dtl.DTLVardef@1ed2444org.highwire.dtl.DTLVardef@1e7f79borg.highwire.dtl.DTLVardef@30e31d_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical AbstractC_FLOATNO C_FIG

immunology↗

bioRxiv2021

Low-dose lung radiotherapy for COVID-19 lung disease: a pre-clinical efficacy study in a bleomycin model of pneumonitis.

PurposeLow-dose whole lung radiotherapy (LDLR) has been proposed as a treatment for patients with acute respiratory distress syndrome associated with SARS-CoV-2 infection and clinical trials are underway. There is an urgent need for preclinical evidence to justify this approach and inform dose, scheduling and mechanisms of action. Materials and methodsFemale C57BL/6 mice were treated with intranasal bleomycin sulphate (7.5 or 11.25 units/kg, day 0), then exposed to whole lung radiation therapy (0.5, 1.0, 1.5 Gy or sham, day 3). Bodyweight was measured daily and lung tissue harvested for histology and flow cytometry on day 10. Computed tomography (CT) lung imaging was performed pre-radiation (day 3) and pre-endpoint (day 10). ResultsBleomycin caused pneumonitis of variable severity which correlated with weight loss. LDLR at 1.0 Gy was associated with a significant increase in the proportion of mice recovering to 98% of initial bodyweight and a proportion of these mice exhibited less severe histopathological lung changes. Mice experiencing moderate initial weight loss were more likely to respond to LDLR than those experiencing severe initial weight loss. Additionally, LDLR (1.0 Gy) significantly reduced bleomycin-induced increases in interstitial macrophages, CD103+ dendritic cells and neutrophil-DC hybrids. Overall,bleomycin-treated mice exhibited significantly higher percentages of non-aerated lung in left than right lungs and LDLR (1.0 Gy) prevented further reductions in aerated lung volume in right but not left lungs. LDLR at 0.5 and 1.5 Gy did not modulate bodyweight or flow cytometric readouts of bleomycin-induced pneumonitis. ConclusionsOur data support the concept that LDLR can ameliorate acute inflammatory lung injury, identify 1.0 Gy as the most effective dose and provide preliminary evidence that it is more effective in the context of moderate than severe pneumonitis. Mechanistically, LDLR at 1.0 Gy significantly suppressed bleomycin-induced accumulation of pulmonary interstitial macrophages, CD103+ dendritic cells and neutrophil-DC hybrids.

immunology↗

bioRxiv2020

Tolerance induction in memory CD4 T cells is partial and reversible

Memory T cells respond rapidly in part because they are less reliant on heightened levels of costimulatory molecules. This presents challenges to silencing memory T cells in tolerance strategies for autoimmunity or allergy. We find that memory CD4 T cells generated by infection or immunisation survive secondary activation with antigen delivered without adjuvant, regardless of their location in secondary lymphoid organs or peripheral tissues. These cells were, however, functionally altered following a tertiary immunisation with antigen and adjuvant, proliferating poorly but maintaining their ability to produce inflammatory cytokines. Transcriptional and cell cycle analysis of these memory CD4 T cells suggest they are unable to commit fully to cell division potentially because of low expression of DNA repair enzymes. In contrast, these memory CD4 T cells could proliferate following tertiary reactivation by viral re-infection. These data suggest that tolerance induction in memory CD4 T cells is partial and can be reversed.

immunology↗

bioRxiv2019

Upstream translation initiation expands the coding capacity of segmented negative-strand RNA viruses

Segmented negative-strand RNA viruses (sNSVs) include the influenza viruses, the bunyaviruses, and other major pathogens of humans, other animals and plants. The genomes of these viruses are extremely short. In response to this severe genetic constraint, sNSVs use a variety of strategies to maximise their coding potential. Because the eukaryotic hosts parasitized by sNSVs can regulate gene expression through low levels of translation initiation upstream of their canonical open reading frames (ORFs), we asked whether sNSVs could use upstream translation initiation to expand their own genetic repertoires. Consistent with this hypothesis, we showed that influenza A viruses (IAVs) and bunyaviruses were capable of upstream translation initiation. Using a combination of reporter assays and viral infections, we found that upstream translation in IAVs can initiate in two unusual ways: through non-AUG initiation in virally encoded untranslated regions, and through the appropriation of an AUG-containing leader sequence from host mRNAs through viral cap-snatching, a process we termed start-snatching. Finally, while upstream translation of cellular genes is mainly regulatory, for sNSVs it also has the potential to create novel viral gene products. If in frame with a viral ORF, this creates N-extensions of canonical viral proteins. If not, it allows the expression of cryptic overlapping ORFs, which we found were highly conserved in IAV and widely distributed in peribunyaviruses. Thus, by exploiting their hosts capacity for upstream translation initiation, sNSVs can expand still further the coding potential of their extremely compact RNA genomes.

molecular biology↗