Single-Cell Transcriptional Heterogeneity of Neutrophils During Acute Pulmonary Cryptococcus neoformans Infection

Abstract

Neutrophils are critical as the first-line defense against fungal pathogens. Yet, previous studies indicate that neutrophil function is complex during Cryptococcus neoformans (Cn) infection. To better understand the role of neutrophils in acute pulmonary cryptococcosis, we analyzed neutrophil heterogeneity by single-cell transcriptional analysis of immune cells in the lung of Cn-infected mice from a published dataset. We identified neutrophils by reference-based annotation and identified two distinct neutrophil subsets generated during acute Cn infection: A subset with an oxidative stress signature (Ox-PMN) and another with enhanced cytokine gene expression (Cyt-PMN). Based on gene regulatory network and ligand-receptor analysis, we hypothesize that Ox-PMNs interact with the fungus and generate ROS, while Cyt-PMNs are longer-lived neutrophils that indirectly respond to Cn-derived ligands and cytokines to modulate cell-cell communication with dendritic cells and alveolar macrophages. Based on the data, we hypothesized that, during in vivo fungal infection, there is a division of labor in which each activated neutrophil becomes either Ox-PMN or Cyt-PMN.

Host defense against fungal pathogens: Adaptable neutrophil responses and the promise of therapeutic opportunities?

“…Additionally, gene expression patterns illustrate unique spatial localization of these neutrophil subsets to the lung, in the parenchyma, or vasculature depending on the subset [28]. These data suggest that different neutrophil subsets work in tandem to coordinate the host response and clear C. neoformans lung infection [28].…”

“…Recent work examining single-cell transcriptomics of murine neutrophils challenged with Cryptococcus neoformans has also revealed a method of describing neutrophil heterogeneity in the context of a pulmonary infection. Here, authors analyzed a previously published dataset of C. neoformans-infected mice and identified 2 neutrophil subsets specific to C. neoformans infection [28]. In the first, an oxidate stress signature identifies neutrophils (Ox-PMN) that likely interact with C. neoformans directly to generate ROS [28].…”

“…Here, authors analyzed a previously published dataset of C. neoformans-infected mice and identified 2 neutrophil subsets specific to C. neoformans infection [28]. In the first, an oxidate stress signature identifies neutrophils (Ox-PMN) that likely interact with C. neoformans directly to generate ROS [28]. The second subset demonstrates a prominent cytokine gene expression profile from neutrophils (Cyt-PMN) that indirectly respond to C. neoformans-derived ligands and interact more closely with other host immune cells for a coordinated response [28].…”

“…In the first, an oxidate stress signature identifies neutrophils (Ox-PMN) that likely interact with C. neoformans directly to generate ROS [28]. The second subset demonstrates a prominent cytokine gene expression profile from neutrophils (Cyt-PMN) that indirectly respond to C. neoformans-derived ligands and interact more closely with other host immune cells for a coordinated response [28]. Additionally, gene expression patterns illustrate unique spatial localization of these neutrophil subsets to the lung, in the parenchyma, or vasculature depending on the subset [28].…”

“…The second subset demonstrates a prominent cytokine gene expression profile from neutrophils (Cyt-PMN) that indirectly respond to C. neoformans-derived ligands and interact more closely with other host immune cells for a coordinated response [28]. Additionally, gene expression patterns illustrate unique spatial localization of these neutrophil subsets to the lung, in the parenchyma, or vasculature depending on the subset [28]. These data suggest that different neutrophil subsets work in tandem to coordinate the host response and clear C. neoformans lung infection [28].…”