Biology subjects

Mackey, J. B.

Publications and source records attributed to Mackey, J. B..

3 recordsLinked to original sources

bioRxiv2024

Uridine Phosphorylase-1 supports metastasis of mammary cancer by altering immune and extracellular matrix landscapes of the lung

Understanding the mechanisms that facilitate early events in metastatic seeding is key to developing therapeutic approaches to reduce metastasis - the leading cause of cancer-related death. Using whole animal screens in genetically engineered mouse models of cancer we have identified circulating metabolites associated with metastasis. Specifically, we highlight the pyrimidine uracil as a prominent metastasis-associated metabolite. Uracil is generated by neutrophils expressing the enzyme uridine phosphorylase-1 (UPP1), and neutrophil specific Upp1 expression is increased in cancer. Altered UPP1 activity influences expression of adhesion molecules on the surface of neutrophils, leading to decreased neutrophil motility in the pre-metastatic lung. Furthermore, we find that UPP1-expressing neutrophils suppress T-cell proliferation, and the UPP1 product uracil can increase fibronectin deposition in the extracellular microenvironment. Consistently, knockout or inhibition of UPP1 in mice with mammary tumours increases the number of T-cells and reduces fibronectin content in the lung and decreases the proportion of mice that develop lung metastasis. These data indicate that UPP1 influences neutrophil behaviour and extracellular matrix deposition in the lung and suggest that pharmacological targeting of this pathway could be an effective strategy to reduce metastasis.

cancer biology↗

bioRxiv2024

Integrin inactivation slows down neutrophils congesting the pre-metastatic lung in a model of breast cancer

Neutrophils are thought to be critical to the process whereby breast cancers establish an immunosuppressive and tumour cell nurturing pre-metastatic niche before overt metastasis can be detected. However, the spatial localization of neutrophils and their interaction with other cell types in the lung pre-metastatic niche is not well described. We used a spontaneously metastatic mammary cancer model combined with a multiplexed three- and four-dimensional imaging approach to investigate the behaviour of neutrophils in the pre-metastatic niche. Volume fixed tissue three-dimensional imaging showed that approximately 40% of CD8+ T cells are adjacent to neutrophils at this stage. In live tissue, we found neutrophils with impaired intravascular motility congested the capillaries of pre-metastatic lungs potentially obstructing CD8+ T cells. Slowed neutrophil transit was dependent on the conformation of {beta}2-integrin and could be recapitulated by treating non-tumour bearing mice with G-CSF, a potent systemic mediator of granulopoiesis. We found a decrease in L-selectin (CD62L) on neutrophils in the lungs of both mammary tumour bearing and G-CSF treated mice. Finally, we observed differential accumulation of intravenously injected micro-beads in the lung, suggestive of transient circulatory dead spaces which were also dependent on {beta}2-integrin inactivation. Overall, our study proposes that integrin-mediated neutrophil congestion of the alveolar capillaries could contribute to the generation of the pulmonary pre-metastatic niche.

immunology↗

bioRxiv2023

Multimodal decoding of human liver regeneration

The liver has a unique ability to regenerate1,2, however in the setting of acute liver failure (ALF) this regenerative capacity is often overwhelmed and emergency liver transplantation is the only curative option3-5. To advance our understanding of human liver regeneration and to inform design of pro-regenerative therapies, we use paired single-nuclei RNA sequencing (snRNA-seq) combined with spatial profiling of healthy and ALF explant human livers to generate the first single-cell, pan-lineage atlas of human liver regeneration. We uncover a novel ANXA2+ migratory hepatocyte subpopulation which emerges during human liver regeneration, and a corollary migratory hepatocyte subpopulation in a mouse model of acetaminophen (APAP)-induced liver regeneration. Importantly, interrogation of necrotic wound closure and hepatocyte proliferation across multiple timepoints following APAP-induced liver injury in mice demonstrates that wound closure precedes hepatocyte proliferation. 4-D intravital imaging of APAP-induced mouse liver injury identifies motile hepatocytes at the edge of the necrotic area, enabling collective migration of the hepatocyte sheet to effect wound closure. Depletion of hepatocyte ANXA2 expression reduces HGF-induced human and mouse hepatocyte migration in vitro, and abrogates necrotic wound closure following APAP-induced mouse liver injury. Taken together, our work dissects unanticipated aspects of liver regeneration, demonstrating an uncoupling of wound closure and hepatocyte proliferation and uncovering a novel migratory hepatocyte subpopulation which mediates wound closure following liver injury. Therapies designed to promote rapid reconstitution of normal hepatic microarchitecture and reparation of the gut-liver barrier may open up new areas of therapeutic discovery in regenerative medicine.

cell biology↗