Single-cell transcriptome profiling reveals neutrophil heterogeneity in homeostasis and infection

Abstract

The full neutrophil heterogeneity and differentiation landscape remains incompletely characterized. Here we profiled >25,000 differentiating and mature mouse neutrophils using single-cell RNA sequencing to provide a comprehensive transcriptional landscape of neutrophil maturation, function, and fate decision in their steady state and during bacterial infection. Eight neutrophil populations were defined by distinct molecular signatures. The three mature peripheral blood neutrophil subsets arise from distinct maturing bone marrow neutrophil subsets. Driven by both known and uncharacterized transcription factors, neutrophils gradually acquire microbicidal capability as they traverse the transcriptional landscape, representing an evolved mechanism for fine-tuned regulation of an effective but balanced neutrophil response. Bacterial infection reprograms the genetic architecture of neutrophil populations, alters dynamic transition between each subpopulation, and primes neutrophils for augmented functionality without affecting overall heterogeneity. In summary, these data establish a reference model and general framework for studying neutrophil-related disease mechanisms, biomarkers, and therapeutic targets at single-cell resolution.

The Secretive Life of Neutrophils Revealed by Intravital Microscopy

“…They constitute four different sequential stages in the process of neutrophil maturation and up to 24 genes were differentially expressed in each subpopulation. G1 is the more proliferative and less differentiated cluster while G4 showed the higher maturation profile constituting the fully mature neutrophil subpopulation in the BM (Xie et al, 2020).…”

“…These three stages of neutrophil maturation were also found in human BM. Xie et al (2020) have profiled more than 25,000 mouse neutrophils using single-cell RNA sequencing and found four different clusters of neutrophils present in the BM, called G1-4, partially overlapping with the ones identified by Evrard et al (2018). They constitute four different sequential stages in the process of neutrophil maturation and up to 24 genes were differentially expressed in each subpopulation.…”

“…Based on the differential expression of more than 20 genes, in peripheral blood, three different subpopulations (G5a-c) have been identified. Xie et al (2020) showed that blood G5a and G5b are two independent subsets of neutrophils that differentiate from G3 and G4 BM clusters, respectively.…”

“…Very little is currently known about the turnover of tissue resident neutrophils during homeostasis and the mechanisms required to keep these highly cytotoxic cells from causing tissue damage. During Escherichia coli challenge, it was shown that the different neutrophils subsets were still present but the transcriptional activity of several genes increased in each population (Xie et al, 2020).…”

“…Recently, Fluorescent influenza virus (color-flu) has been developed as a means of studying influenza infection in the lungs of mice by IVM. Details of the model and a database of fluorescent dyes, antibodies, and reporter mouse lines that can be used in combination with Color-flu for multicolor analysis have also been reported (Xie et al, 2020). Using this model, pulmonary permeability (by dextran leakage from the lung vessels into the alveolar space) and blood flow speed (by i.v.…”