Biology subjects

Preston, A. E.

Publications and source records attributed to Preston, A. E..

4 recordsLinked to original sources

bioRxiv2024

Iron deficiency causes aspartate-sensitive metabolic and proliferative dysfunction in CD8+ T cells

Iron is an irreplaceable co-factor for metabolism. Iron deficiency affects >1 billion people, causing symptoms including anaemia and impaired immunity. Nevertheless, precisely how iron deprivation impacts immune cell function remains poorly characterised. We therefore interrogated how physiologically low iron availability affected activated CD8+ T cell metabolism and function, using multi-omic and metabolic labelling approaches. Iron limitation profoundly stalled proliferation without influencing cell viability, altered histone methylation status and disrupted mitochondrial membrane potential. Consistently, metabolism of glucose and glutamine in the TCA cycle was limited, indeed TCA cycle activity was partially reversed to a reductive trajectory. Previous studies have shown mitochondria-derived aspartate is crucial for proliferation of transformed cells. Surprisingly, we found aspartate was increased in stalled iron deficient CD8+ T-cells, but was not utilised cytosolically for nucleotide synthesis, likely due to trapping within depolarised mitochondria. Conversely, exogenous aspartate, which directly accesses the cytosol, markedly rescued the clonal expansion of even severely iron-deficient CD8+ T-cells. Overall, iron scarcity creates a mitochondrial-located metabolic bottleneck impairing T-cells, which can be bypassed by resupplying inhibited biochemical processes with aspartate. These findings reveal molecular consequences of iron deficiency for CD8+ T cell function, providing mechanistic insight into the basis for immune impairment during iron deficiency.

immunology↗

bioRxiv2023

Ancient genomic linkage couples metabolism with erythroid development

Generation of mature cells from progenitors requires tight coupling of differentiation and metabolism. During erythropoiesis, erythroblasts are required to massively upregulate globin synthesis then clear extraneous material and enucleate to produce erythrocytes1-3. Nprl3 has remained in synteny with the -globin genes for >500 million years4, and harbours the majority of the -globin enhancers5. Nprl3 is a highly conserved inhibitor of mTORC1, which controls cellular metabolism. However, whether Nprl3 itself serves an erythroid role is unknown. Here, we show that Nprl3 is a key regulator of erythroid metabolism. Using Nprl3-deficient fetal liver and adult competitive bone marrow - fetal liver chimeras, we show that NprI3 is required for sufficient erythropoiesis. Loss of Nprl3 elevates mTORC1 signalling, suppresses autophagy and disrupts erythroblast glycolysis and redox control. Human CD34+ progenitors lacking NPRL3 produce fewer enucleated cells and demonstrate dysregulated mTORC1 signalling in response to nutrient availability and erythropoietin. Finally, we show that the -globin enhancers upregulate NprI3 expression, and that this activity is necessary for optimal erythropoiesis. Therefore, the anciently conserved linkage of NprI3, -globin and their associated enhancers has enabled coupling of metabolic and developmental control in erythroid cells. This may enable erythropoiesis to adapt to fluctuating nutritional and environmental conditions.

cell biology↗

bioRxiv2023

Cellular iron governs the host response to malaria

Malaria and iron deficiency are major global health problems with extensive epidemiological overlap. Iron deficiency-induced anaemia can protect the host from malaria by limiting parasite growth. On the other hand, iron deficiency can significantly disrupt immune cell function. However, the impact of host cell iron scarcity beyond anaemia remains elusive in malaria. To address this, we employed a transgenic mouse model carrying a mutation in the transferrin receptor (TfrcY20H/Y20H), which limits the ability of cells to internalise iron from plasma. At homeostasis TfrcY20H/Y20H mice appear healthy and are not anaemic. However, TfrcY20H/Y20H mice infected with Plasmodium chabaudi chabaudi AS showed significantly higher peak parasitaemia and body weight loss. We found that TfrcY20H/Y20H mice displayed a similar trajectory of malaria-induced anaemia as wild-type mice, and elevated circulating iron did not increase peak parasitaemia. Instead, P. chabaudi infected TfrcY20H/Y20H mice had an impaired innate and adaptive immune response, marked by decreased cell proliferation and cytokine production. Moreover, we demonstrated that these immune cell impairments were cell-intrinsic, as ex vivo iron supplementation fully recovered CD4 T cell and B cell function. Despite the inhibited immune response and increased parasitaemia, TfrcY20H/Y20H mice displayed mitigated liver damage, characterised by decreased parasite sequestration in the liver and an attenuated hepatic immune response. Together, these results show that host cell iron scarcity inhibits the immune response but prevents excessive hepatic tissue damage during malaria infection. These divergent effects shed light on the role of iron in the complex balance between protection and pathology in malaria.

immunology↗

bioRxiv2022

Plasma iron controls neutrophil production and function

Low plasma iron (hypoferremia) induced by hepcidin is a conserved inflammatory response that protects against infections but inhibits erythropoiesis. How hypoferremia influences leukocytogenesis is unclear. Using proteomic data, we predicted that neutrophil production would be profoundly more iron-demanding than generation of other white blood cell types. Accordingly in mice, hepcidin-mediated hypoferremia substantially reduced numbers of granulocytes but not monocytes, lymphocytes or dendritic cells. Neutrophil rebound after anti-GR1-induced neutropenia was blunted during hypoferremia, but was rescued by supplemental iron. Similarly, hypoferremia markedly inhibited pharmacologically-stimulated granulopoiesis mediated by GCSF and inflammation-induced accumulation of neutrophils in the spleen and peritoneal cavity. Furthermore, hypoferremia specifically altered neutrophil effector functions, suppressing antibacterial mechanisms but enhancing mitochondrial ROS-dependent NETosis associated with chronic inflammation. Notably, antagonising endogenous hepcidin during acute inflammation enhanced production of neutrophils. We propose plasma iron modulates the profile of innate immunity by controlling monocyte-to-neutrophil ratio and neutrophil activity in a therapeutically targetable system.

immunology↗