Biology subjects

Marriott, H. M.

Publications and source records attributed to Marriott, H. M..

4 recordsLinked to original sources

bioRxiv2022

The EGFR/ErbB inhibitor neratinib modifies the neutrophil phosphoproteome and promotes apoptosis and clearance by airway macrophages

Dysregulated neutrophilic inflammation can be highly destructive in chronic inflammatory diseases due to prolonged neutrophil lifespan and continual release of histotoxic mediators in inflamed tissues. Therapeutic induction of neutrophil apoptosis, an immunologically silent form of cell death, may be beneficial in these diseases, provided that the apoptotic neutrophils are efficiently cleared from the tissue. Our previous research identified ErbB inhibitors as able to induce neutrophil apoptosis and reduce neutrophilic inflammation both in vitro and in vivo (Rahman et al., 2019). Here we extend that work using a clinical ErbB inhibitor, neratinib, which has the potential to be repurposed in inflammatory diseases. We show that neratinib reduces neutrophilic migration to an inflammatory site in zebrafish larvae. Neratinib upregulates efferocytosis and reduces the number of persisting neutrophil corpses in mouse models of acute, but not chronic, lung injury, suggesting the drug may have therapeutic benefits in acute inflammatory settings. Phosphoproteomics analysis of human neutrophils shows that neratinib modifies the phosphorylation of proteins regulating apoptosis, migration and efferocytosis. This work identifies a potential mechanism for neratinib in treating acute lung inflammation by upregulating the clearance of dead neutrophils and, through examination of the neutrophil phosphoproteome, provides important insights into the mechanisms by which this may be occurring.

immunology↗

bioRxiv2019

Macrophages utilize mitochondrial fission to enhance mROS production during responses to Streptococcus pneumoniae

Immunometabolism and regulation of mitochondrial reactive oxygen species (mROS) are critical determinants of the immune effector phenotype of differentiated macrophages. Mitochondrial function requires dynamic fission and fusion, but whether effector function is associated with altered dynamics during bacterial responses is unknown. We show that macrophage mitochondria undergo fission after 12 h of progressive ingestion of live Streptococcus pneumoniae (pneumococci). Fission is associated with progressive reduction in oxidative phosphorylation but increased mROS generation. Fission is enhanced by mROS production, PI3K{gamma} signaling and by cathepsin B, but not by inflammasome activation or IL-1{beta} generation. Reduced fission following PI3K{gamma} or cathepsin B inhibition is associated with reduced mROS generation and bacterial killing. Fission is associated with Parkin recruitment to mitochondria, but not mitophagy. Fission occurs upstream of apoptosis induction and independently of caspase activation. During macrophage innate responses to live bacteria mitochondria shift from oxidative phosphorylation and ATP generation to mROS production and microbicidal responses with a progressive shift towards mitochondrial fission.

immunology↗

bioRxiv2019

The mouse lung early cellular innate immune response is not sufficient to control fungal infection with Cryptococcus neoformans

Cryptococcus neoformans causes life-threatening infection in the immunocompromised. This and other opportunistic pathogens are an increasing threat as immunosuppression increases globally. To counter antibiotic resistance, there is precedent for developing immune enhancing therapy. However, our understanding of how immunocompetent patients resolve these infections is poor as opportunistic infections typically resolve subclinically. Because this has led to a lack of clinical data, we rely on animal models. Current in vivo infection models either lack mammalian immunity or are not compatible with long term high content imaging required to model the complexities of human host-pathogen interactions. Therefore, we have developed an ex vivo murine precision cut lung slice (PCLS) model to understand innate immunity in cryptococcosis. C57BL/6 mice were sacrificed 0 or 24 hours post infection with KN99 cryptococci. Lungs were inflated with 37{degrees}C agarose, 300m thick PCLS were prepared on a vibratome and imaged by confocal or wide-field fluorescence microscopy. Using PCLS and immunofluorescence, we demonstrate cryptococcal replication and clearance rates are balanced over the first 24 hours of infection. Cell-mediated immunity is alveolar macrophage centric, although alveolar macrophages demonstrate limited phagocytosis of cryptococci and enable intracellular cryptococcal replication. Cryptococcus neoformans responded to the lung environment by forming enlarged cells, although these were not large enough to be titan cells. To further understand cryptococcal proliferation in vivo, we also infected animals with plb1 mutant Cryptococcus neoformans that has been shown to exhibit proliferation defects in vivo. We found no difference in fungal burden with plb1 infected animals 24 hours post infection, but observed significantly larger fungal cells and no incidences of phagocytosis. Thus, the PCLS model can be used to assess the lung immune response early in cryptococcal infection, demonstrating that resident lung macrophages cannot control cryptococcal infection and offer an intracellular niche for Cryptococcus neoformans growth.

immunology↗

bioRxiv2017

Polymersomes Targeting Mononuclear Phagocytes

Mononuclear phagocytes such as monocytes, tissue-specific macrophages and dendritic cells are primary actors in both innate and adaptive immunity, as well as tissue homoeostasis. They have key roles in a range of physiological and pathological processes, so any strategy targeting these cells will have wide-ranging impact. These phagocytes can be parasitized by intracellular bacteria, turning them from housekeepers to hiding places and favouring chronic and/or disseminated infection. One of the most infamous is the bacteria that cause tuberculosis, which is the most pandemic and one of the deadliest disease with one third of the worlds population infected, and 1.8 million deaths worldwide in 2015. Here we demonstrate the effective targeting and intracellular delivery of antibiotics to both circulating monocytes and resident macrophages, using pH sensitive nanoscopic polymersomes made of poly(2-(methacryloyloxy)ethyl phosphorylcholine)-co-poly(2-(di-isopropylamino)ethyl methacrylate) (PMPC-PDPA). Polymersome selectivity to mononuclear phagocytes is demonstrated and ascribed to the polymerised phosphorylcholine motifs affinity toward scavenger receptors. Finally, we demonstrate the successful exploitation of this targeting for the effective eradication of intracellular bacteria that cause tuberculosis Mycobacterium tuberculosis as well as other intracellular parasites including the Mycobacterium bovis, Mycobacterium marinum and the most common bacteria associated with antibiotic resistance, the Staphylococcus aureus.

immunology↗