mTOR-dependent translation amplifies microglia priming in aging mice.

peer reviewedMicroglia maintain homeostasis in the brain. However, with age, they become primed and respond more strongly to inflammatory stimuli. We show here that microglia from aged mice had upregulated mTOR complex 1 signaling controlling translation, as well as protein levels of inflammatory mediators. Genetic ablation of mTOR signaling showed a dual yet contrasting effect on microglia priming: it caused an NF-κB-dependent upregulation of priming genes at the mRNA level; however, mice displayed reduced cytokine protein levels, diminished microglia activation, and milder sickness behavior. The effect on translation was dependent on reduced phosphorylation of 4EBP1, resulting in decreased binding of eIF4E to eIF4G. Similar changes were present in aged human microglia and in damage-associated microglia, indicating that upregulation of mTOR-dependent translation is an essential aspect of microglia priming in aging and neurodegeneration

Assessing mRNA translation in mouse adult microglia and bone-marrow-derived macrophages

Summary: Protein synthesis, or mRNA translation, is the biological process through which genetic information stored in messenger RNAs is encoded into proteins. Here, we present an optimized protocol for assessing the translation rate in mouse adult microglia and cultured bone-marrow-derived macrophages. We describe steps for isolating cells, treating them with a puromycin-analog probe, and fluorescently labeling the puromycylated-polypeptide chains. We then detail their quantification by flow cytometry or with a fluorescent plate reader.For complete details on the use and execution of this protocol, please refer to Keane et al. (2021).1 : Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics

Systemic alterations in neutrophils and their precursors in early-stage chronic obstructive pulmonary disease

Summary: Systemic inflammation is established as part of late-stage severe lung disease, but molecular, functional, and phenotypic changes in peripheral immune cells in early disease stages remain ill defined. Chronic obstructive pulmonary disease (COPD) is a major respiratory disease characterized by small-airway inflammation, emphysema, and severe breathing difficulties. Using single-cell analyses we demonstrate that blood neutrophils are already increased in early-stage COPD, and changes in molecular and functional neutrophil states correlate with lung function decline. Assessing neutrophils and their bone marrow precursors in a murine cigarette smoke exposure model identified similar molecular changes in blood neutrophils and precursor populations that also occur in the blood and lung. Our study shows that systemic molecular alterations in neutrophils and their precursors are part of early-stage COPD, a finding to be further explored for potential therapeutic targets and biomarkers for early diagnosis and patient stratification