Biology subjects

MacDonald, A. S.

Publications and source records attributed to MacDonald, A. S..

13 recordsLinked to original sources

bioRxiv2026

Conventional dendritic cells type I with an enhanced type-I-IFN signaling underpin anti-tumor immune responses in brain metastases

Brain metastases are associated with poor prognosis. A better understanding of anti-tumor immune responses in the context of immune specialized microenvironment of the brain is required to develop improved therapeutic strategies for this disease. We demonstrate that the conventional dendritic cells type 1 (cDC1) gene signature positively correlates with a prolonged BrM-dependent survival in melanoma and breast cancer patients. Furthermore, intracranial anti-tumor immune responses in preclinical BrM models consistently rely on cDC1s for tumor growth control, BrM-dependent survival and maintenance of the intra-tumoral CD8+ T cell pool, in contrast to variable, cancer type-dependent cDC1 roles in extracranial tumors. This is underpinned by tumor site-specific cDC1 molecular profiles with distinct Toll like receptor repertoires, upregulation of co-stimulatory molecules and IL-12, and enhanced type-I-IFN signaling in intracranial cDC1s, with the latter driving increased cDC1 activation. cDC1s also promote the conversion of progenitor exhausted CD8+ T cells to transient effectors, which is further enhanced by immune checkpoint blockade therapy. These findings pinpoint cDC1s as a major cell population of interest in the development of future immunotherapies for BrM. Significance statementCharacteristics of immune cells and tumor microenvironment in brain metastases (BrM) are distinct to extracranial tumor sites and characterized by special immunological barriers and suppressive stroma. Conventional dendritic cells type 1 (cDC1s), which are key regulators of anti-tumor immunity, remain largely unexplored in this context. This study deepens our understanding of how anti-tumor immune responses differ between BrM and extracranial tumors by revealing BrM-specific phenotype and function of cDC1s, with the latter being critical for anti-tumor immunity in BrM even in cancer models where extracranial cDC1s demonstrate pro-tumorigenic function, highlighting cDC1s as universal regulators of intracranial anti-tumor immunity. Our study suggests that tumor site-specific augmentation of cDC1s should be pursued to enhance the efficacy of immunotherapies in BrM.

cancer biology↗

bioRxiv2026

Trypanosoma brucei infection remodels the uterine immune environment and drives neuroendocrine dysfunction

Human African Trypanosomiasis (HAT) or sleeping sickness is a systemic parasitic infection caused by the protozoan parasite Trypanosoma brucei. HAT is associated with substantial immunological, metabolic, and neurological pathology. Although reproductive dysfunction has previously been recognised in both human and experimental T. brucei infection, whether parasites can directly infiltrate the female reproductive tract (FRT), and how infection may reshape the FRT immune landscape remains poorly understood. Using a murine model of T. brucei infection we reveal that parasites are localised in the uterine lining (endometrium) during both acute and chronic infection stages in mice. Chronic T. brucei infection was associated with progressive fat wasting, disruption of the reproductive (oestrous) cycle, uterine and ovarian atrophy, and extensive transcriptional dysregulation across the hypothalamic-pituitary-gonadal (HPG) axis. Acute and chronic infection induced remodelling of the uterine immune landscape, characterised by T cell infiltration, pro-inflammatory myeloid activation, alongside broader type 1 inflammatory changes across reproductive tissues and HPG components. Ovarian pathology was accompanied by follicular degeneration, a reduction in corpora lutea and alterations to steroidogenic pathways. Hormonal rescue with selective oestrogen receptor modulator, tamoxifen, restored uterine morphology and prevented oestrous cycle arrest, but did not reverse the infection-induced uterine immune remodelling, indicating that endocrine dysfunction and infection-driven inflammation are distinct processes. Taken together, these findings identify the FRT as a major target of T. brucei infection and demonstrate how chronic parasitic infection can disrupt reproductive physiology through a combination of immune, endocrine, and metabolic pathways. They also highlight the need to specifically assess the FRT in other models of systemic inflammation. Author summaryHuman and animal African trypanosomiasis, also known as sleeping sickness and nagana, are caused by the parasite, Trypanosoma brucei. These chronic infections are associated with immune changes across the body as well as changes to metabolism and neurology. In both humans and animals, infection has been linked to poor reproductive outcomes, including miscarriage, foetal growth restriction and menstrual irregularities. However, whether T. brucei can infiltrate into the uterus of infected mice and whether this presence can alter the local immune cell dynamics remains poorly understood. Using an animal model of acute and chronic T. brucei infection, we were able to detect the parasites within the uterus of infected female mice. In addition, we found that the immune cell profile from the uterus of infected females was more pro-inflammatory during T. brucei infection. During chronic infection, we found that animals showed progressive fat wastage, disruption of reproductive cycling, and marked uterine and ovarian shrinkage. When we administered an oestrogen-like compound, we found that uterine and ovarian size changes were hormone-dependent but the immune changes in the uterus were hormone-independent.

immunology↗

bioRxiv2025

Pulmonary macrophage subsets display distinct metabolic responses to polarising stimuli in vivo

Macrophage activation is underpinned by metabolic changes required to fight infection, resolve inflammation and enable effective wound healing. While metabolic control of macrophage activation is increasingly understood in culture systems in vitro, it remains poorly understood in more complex in vivo settings, like the lung. Here we applied novel flow cytometry based immunometabolic techniques to profile immune cell metabolism in the murine lung. We revealed a surprising role for glucose in naive alveolar macrophages (AMs) that was retained by AMs polarised in vivo with either interleukin-4 (IL-4) or lipopolysaccharide (LPS). We identified that naive interstitial macrophages (IMs) were dependent on mitochondrial and glucose metabolism, IMs polarised with IL-4 failed to induce metabolic alterations but displayed a glycolytic phenotype following LPS exposure as they adopted an M1 like metabolic profile. We also demonstrated that AMs were metabolically less responsive than IMs to intranasal delivery of LPS, but upregulated glycolysis and metabolic features of M2 polarisation (defined in vitro) in response to intranasal IL-4, including oxidative phosphorylation (OXPHOS), fatty acid oxidation (FAO) and arginine metabolism. Finally, we identified AM M2 polarisation as highly sensitive to glucose inhibition ex vivo. Thus, lung macrophage subsets display distinct metabolic responses to polarising stimuli in vivo. HighlightsO_LINaive alveolar macrophages require glucose metabolism despite residing in a low glucose environment. C_LIO_LIAlveolar macrophages are more responsive to IL-4 in vivo than LPS upregulating oxidative metabolism, lipid metabolism and glycolysis. C_LIO_LIInterstitial macrophages adopt a glycolytic phenotype characteristic of M1 BMDMs in vitro following in vivo LPS administration. C_LIO_LIAlternatively activated alveolar macrophages are extremely sensitive to glucose inhibition ex vivo. C_LI

immunology↗

bioRxiv2025

Hallmarks and metabolic regulation of type 2 activated human lung macrophages

Although human lung macrophages are heterogenous and play key roles during health and disease, the mechanisms that govern their activation and function are unclear, particularly in type 2 settings. Our understanding of how human lung macrophages respond to inflammatory signals have predominantly relied on cell lines or peripheral blood derived cells, which have a limited capacity to reflect the complexity of tissue macrophage responses. Therefore, we isolated macrophages from resected human lung tissue and stimulated them ex vivo under type 2 (IL-4, IL-13, or IL-4 + IL-13) or type 1 (IFN{gamma} + LPS) conditions. Human lung macrophages stimulated with IL-4/13, alone or in combination, significantly upregulated expression of the chemokines CCL17, CCL18 and CCL22, along with the transglutaminase TGM2 and the lipoxygenase ALOX15. This type 2 activation profile was distinct from LPS + IFN{gamma} activated human lung macrophages, which upregulated IL6, IL8, IL1{beta}, TNF and CHI3L1 (YKL-40). Further, type 2 activated human lung macrophage products showed differential metabolic reliance for their induction, with IL-4/13 induced CCL22 being glycolytically controlled, while ALOX15 was regulated by fatty acid oxidation. These data clarify hallmarks of human lung macrophage activation and polarisation in addition to revealing novel metabolic regulation of type 2 markers.

immunology↗

bioRxiv2025

Macrophages promote collagen deposition through circadian regulation of fibroblasts

Collagen deposition in fibroblasts, the primary collagen-producing cells, is regulated by both macrophages and the circadian rhythm, although how these regulatory processes interact with one another is unknown. Here, we reveal that macrophage-fibroblast interaction enhances collagen deposition which requires a functional circadian rhythm. This response is also dependent on macrophage polarisation status, where M0 (naive) and M1 (pro-inflammatory) macrophages require direct cell-cell contact; whereas M2 (anti-inflammatory) macrophages utilise an additional mechanism through secreted soluble factors that strengthen circadian rhythms and significantly increase collagen deposition in fibroblasts, independent of cell-cell contact. Using mass spectrometry proteomics analysis, we identified PDGFA as a key factor in induction of circadian amplitude in fibroblasts. Crucially, macrophages lacking PDGFA showed diminished ability to modulate fibroblast circadian rhythms and collagen production. Further, in fibroblasts with impaired circadian rhythms, neither macrophages nor macrophage-secreted factors are capable of inducing collagen deposition. These results confirmed that the collagen secretory pathway is also under circadian clock control in lung fibroblasts, and demonstrated that macrophages influence collagen deposition via circadian clock mediated mechanisms. In conclusion, our findings highlight M2-derived PDGFA as a key macrophage-derived factor in extracellular matrix remodelling.

cell biology↗

bioRxiv2024

Aspergillus-mediated allergic airway inflammation is triggered by dendritic cell recognition of a defined spore morphotype, a process that can be targeted via antifungal therapeutics.

BackgroundExposure to fungi, especially Aspergillus fumigatus (A.f.), can elicit potent allergic inflammation that triggers and worsens asthmatic disease. Dendritic cells (DCs), initiate allergic inflammatory responses to allergic stimuli. However, it is unclear if A.f. spores during isotropic growth (early spore swelling) can activate DCs to initiate allergic responses or if germination is required. This lack of basic understanding of how A.f. causes disease is a barrier to the development of new treatments. ObjectiveTo show that a precise A.f. morphotype stage during spore swelling can trigger DCs to mediate allergic inflammatory responses and ascertain if antifungal therapeutics can be effective at suppressing this process. MethodsWe employed an A.f. strain deficient in pyrimidine biosynthesis ({Delta}pyrG) to generate populations of A.f. spores arrested at different stages of isotropic growth (swelling) via temporal removal of uracil and uridine from growth media. These arrested spore stages were cultured with bone marrow derived DCs (BMDCs), and their activation measured via flow cytometry and ELISA to interrogate which growth stage was able to activate BMDCs. These BMDCs were then adoptively transferred into the airways, to assess if they were able to mediate allergic inflammation in naive recipient mice. Allergic airway inflammation in vivo was determined via flow cytometry, ELISA and qPCR. This system was also used to determine if antifungal drug (itraconazole) treatment could alter early stages of spore swelling and therefore BMDC activation and in vivo allergic inflammation upon adoptive transfer. ResultsWe found that A.f. isotropic growth is essential to trigger BMDC activation and mediate allergic airway inflammation. Furthermore, using time arrested A.f. stages, we found that least 3h in growth media enabled spores to swell sufficiently to activate BMDCs to elicit allergic airway inflammation in vivo. Incubation of germinating A.f. with itraconazole reduced spore swelling and partially reduced their ability to activate BMDCs to elicit in vivo allergic airway inflammation. ConclusionIn summary, our results have pinpointed the precise stage of A.f. development when germinating spores are able to activate DCs to mediate downstream allergic airway inflammation. Furthermore, we have identified that antifungal therapeutics can be effective in reducing the potential of A.f. spores to stimulate allergic responses, highlighting a potential mechanism by which antifungal treatment might help to prevent the development of fungal allergy.

immunology↗

bioRxiv2023

Mgl2+ cDC2s coordinate fungal allergic airway type 2, but not type 17, inflammation.

Fungal spores are abundant in the environment and a major cause of asthma. Originally characterised as a type 2 inflammatory disease, allergic airway inflammation that underpins asthma can also involve type 17 inflammation, which can exacerbate disease causing failure of treatments tailored to inhibit type 2 factors. However, the mechanisms that determine the host response to fungi, which can trigger both type 2 and type 17 inflammation in allergic airway disease, remain unclear. We found that CD11c+ DCs and CD4+ T cells are essential for development of both type 2 and type 17 airway inflammation in mice when repeatedly exposed to inhaled spores. Single cell RNA-sequencing enabled the development of multi-parameter cytometry that identified allergic inflammation dramatically altered the proportion of numerous DC clusters in the lung, but that only two of these (Mgl2+ cDC2s and CCR7+ DCs) migrated to the dLNs. Targeted removal of several DC subsets revealed that only Mgl2+ cDC2 depletion dramatically reduced type 2, but not type 17, anti-fungal allergic airway inflammation. These data highlight distinct DC subsets are potential therapeutic targets for the treatment of pulmonary fungal disease.

immunology↗

bioRxiv2023

Engineering the glioblastoma microenvironment using TLR7/8 agonist-complexed graphene oxide nanosheets

The glioblastoma (GBM) microenvironment is characterised as immunologically cold, with immunosuppressive components that compromise the efficacy of current immunotherapies. Tumour associated macrophages and microglia (TAMMs) that are activated towards an immunosuppressive, pro-tumoral state have been identified as major contributing factors to the coldness of GBM, while further promoting tumour progression and resistance to therapy. Based on this understanding, strategies such as macrophage reprogramming have been explored but have so far been limited by poor delivery and retention of reprogramming agents to the target cell populations within the GBM microenvironment. Consequently, clinical efficacy of such approaches has thus far shown limited success. Two-dimensional, graphene oxide (GO) nanosheets have been demonstrated to spread readily throughout the entire tumour microenvironment following a single intratumoral injection, interacting primarily with TAMMs. The current study aimed to investigate whether the immunosuppressive character of TAMMs in GBM can be ameliorated using GO sheets as a vector system to selectively deliver a TLR7/8 agonist (Resiquimod, R848), into these populations. GO enhanced the activity of R848 and induced the expression of M1-like markers on bone marrow derived macrophages in vitro. Using multi-parameter flow cytometry and histological analysis in a syngeneic, orthotopic mouse model of GBM, we observed that a single intratumoral injection of GO:R848 complex significantly elevated the proportion of macrophages and microglia expressing MHCII, TNF and CD86 (associated with a pro-inflammatory, anti-tumoral state), while downregulating their expression of the M2 markers ARG1 and YM1 (associated with an anti-inflammatory, pro-tumoral state). This local complex administration inhibited tumour progression and significantly reduced tumour burden. These data illustrate that immunomodulatory GO nanosheets can effectively alter the immune landscape of GBM and modulate the wider GBM microenvironment. ToC Image O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=126 SRC="FIGDIR/small/558196v1_ufig1.gif" ALT="Figure 1"> View larger version (42K): org.highwire.dtl.DTLVardef@199bdb0org.highwire.dtl.DTLVardef@7473c3org.highwire.dtl.DTLVardef@15c14c6org.highwire.dtl.DTLVardef@57fdeb_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2023

Allergen-induced airway matrix remodelling in mice can be prevented or reversed by targeting chitinase-like proteins.

Chitinase-like proteins (CLPs) are biomarkers of inflammation and airway remodelling in asthma, yet their direct contribution towards disease pathogenesis is unknown. Using a mouse model of allergen-induced type 2/type 17 airway inflammation we sought to directly investigate the role of the murine CLPs Ym1 and Ym2 during chronic lung pathology. Data demonstrated distinct chronic inflammatory roles for Ym2, IL-13, and IL-17a signalling pathways. Notably, only CLPs were key for initiating the pathogenic accumulation and re-organisation of the pulmonary extracellular matrix (ECM) environment. Furthermore, inhibition of CLPs after chronic pathology developed, reversed airway remodelling independently of chronic inflammation. These studies disentangle chronic IL-13 and IL-17a signalling from the development of allergic airway remodelling and instead highlight a central role for CLPs, which provides new avenues to therapeutically target aberrant ECM accumulation.

immunology↗

bioRxiv2021

Genotype and Th2 cells control monocyte to tissue resident macrophage differentiation during nematode infection of the pleural cavity

The recent revolution in tissue-resident macrophage biology has resulted largely from murine studies performed in the C57BL/6 strain. Here, we provide a comprehensive analysis of immune cells in the pleural cavity using both C57BL/6 and BALB/c mice. Unlike C57BL/6 mice, naive tissue-resident Large Cavity Macrophages (LCM) of BALB/c mice failed to fully implement the tissue residency program. Following infection with a pleural-dwelling nematode these pre-existing differences were accentuated with LCM expansion occurring in C57BL/6 but not BALB/c mice. While infection drove monocyte recruitment in both strains, only in C57BL/6 mice were monocytes able to efficiently integrate into the resident pool. Monocyte to macrophage conversion required both T cells and IL-4R signalling. Host genetics are therefore a key influence on tissue resident macrophage biology, and during nematode infection Th2 cells control the differentiation pathway of tissue resident macrophages. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=198 SRC="FIGDIR/small/472661v1_ufig1.gif" ALT="Figure 1"> View larger version (69K): org.highwire.dtl.DTLVardef@bba5e1org.highwire.dtl.DTLVardef@1876aa4org.highwire.dtl.DTLVardef@16a6b1corg.highwire.dtl.DTLVardef@19e18b6_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2020

IL-13 deficiency exacerbates lung damage and impairs epithelial-derived type 2 molecules during nematode infection

IL-13 plays a key role during protective type 2 immune responses at mucosal sites, such as during infection with nematodes. However, dysregulation of IL-13 can also contribute to the pathogenesis of atopic and fibrotic diseases such as allergic asthma. Matrix remodelling is an important component of repair processes in the lung but also a hallmark of chronic conditions involving fibrosis. Hence, understanding the role of IL-13 in tissue remodelling has important clinical implications. Since IL-13 shares receptors and signalling pathways with IL-4, disentangling the relative contributions of these type 2 cytokines has been challenging. Additionally, little is known about the singular role of IL-13 following acute tissue injury. In this study, we used Nippostrongylus brasiliensis infection as a model of acute lung tissue damage comparing responses between WT and IL-13-deficient mice, in which IL-4 signalling is intact. Importantly, we found that IL-13 played a critical role in limiting tissue injury and haemorrhaging in the lung following infection. Through proteomic and transcriptomic profiling, we identified IL-13-dependent changes in matrix and associated regulators. We further showed that IL-13 is required for the induction of epithelial-derived type 2 effector molecules such as RELM- and surfactant protein D. Pathway analyses predicted that IL-13 was heavily involved in the induction of cellular stress responses and regulation of lung epithelial cell differentiation by suppression of Foxa2 pathways. Thus, we propose that IL-13 has tissue-protective functions during lung injury and regulates epithelial cell responses during type 2 immunity in this acute setting.

immunology↗

bioRxiv2020

The neutrophil antimicrobial peptide cathelicidin promotes Th17 differentiation

The host defence peptide cathelicidin (LL-37 in humans, mCRAMP in mice) is released from neutrophils by de-granulation, NETosis and necrotic cell death; it has potent antibacterial, antiviral and antifungal activity as well as being a powerful immunomodulator. It is released in proximity to CD4+ T cells during inflammatory and infectious disease but its impact on T cell phenotype is scarcely understood. Here we demonstrate that cathelicidin is a powerful Th17 potentiating factor which increases expression of the aryl hydrocarbon receptor (AHR) and the ROR{gamma}t transcription factor, in a TGF-{beta}1-dependent manner. We show that cathelicidin induces IL-17F production in particular, and that its induction of IL-17A+F+ double producing cells is dependent on AHR while its induction of IL-17F single producing cells is not. In the presence of TGF-{beta}1, cathelicidin profoundly suppressed IL-2 and down-regulated T-bet, specifically directing T cells away from Th1 and into a Th17 phenotype. Strikingly, Th17, but not Th1 cells were protected from apoptotic death by cathelicidin, in the first example of a neutrophil-released mediator inducing survival of a T cell subset. Finally, we show that cathelicidin is released by neutrophils in mouse lymph nodes following inoculation of heat-killed Salmonella typhimurium and that cathelicidin-deficient mice have suppressed Th17 responses during inflammation, but not at steady state. We propose that the release of cathelicidin by neutrophils is required for maximal Th17 differentiation and IL-17 production by CD4+ T cells, and that this is one method by which early neutrophilia directs subsequent adaptive immune responses with some sophistication.

immunology↗

bioRxiv2020

Mapping the influence of the gut microbiota on small molecules in the brain through mass spectrometry imaging

BackgroundThe gut microbiota is known to influence virtually all facets of human health. Recent work has highlighted a potential role for the gut microbiota in neurological health through the microbiome-gut-brain axis. Microbes can influence the brain both directly and indirectly; through neurotransmitter production, induction of host immunomodulators, or through the release or induction of other microbial or host molecules. MethodsHere we used mass spectrometry imaging (MSI), a label-free imaging tool, to map the molecular changes that occur in the murine gut and brain in germ-free, antibiotic-treated and control mice. ResultsWe determined the spatial distribution and relative quantification of neurotransmitters and their precursors across brain and gut sections in response to the microbiome. Using untargeted MSI of small molecules, we detected a significant change in the levels of four identified metabolites in the brains of germ-free animals compared to controls; vitamin B5, 3-hydroxy-3-methylglutaric acid, 3-methyl-4-(trimethylammonio)butanoate and 4-(trimethylammonio)pentanoate. However, antibiotic treatment induced no significant changes in these metabolites in the brain after one week of treatment. ConclusionsThis work exemplifies the utility of MSI as a tool in determining the spatial distribution and quantification of bacterial and host metabolites in the gut and brain whilst also offering the potential for discovery of novel mediators of microbiome-gut-brain axis communication.

microbiology↗