Origin and function of non-canonical CX3CR1+ neutrophils

Neutrophils are essential mediators of antimicrobial defense but also instigate inflammatory injury and organ dysfunction. They are also endowed with protective features such as promoting revascularization or suppressing excessive immune activation. We have hypothesized that this heterogeneity of functions originates, in part, from the production of functionally different neutrophils from different granulocytic progenitors, thereby unveiling potential strategies to stimulate or prevent their anti-microbial, inflammatory, or reparative activities by targeting the different granulopoietic pathways. We have generated an integrative transcriptional map of the full neutrophil compartment in mice and humans which, when combined with computational modeling and fate mapping studies, revealed a novel granulopoietic path that produces a distinct population of CX3CR1+ neutrophils. In vivo profiling of these neutrophils reveals distinct phenotype, distribution in tissues and lifespan when compared with canonical neutrophils, suggesting fundamentally different biological properties of the two populations. Further preliminary studies indicate that these neutrophils acquire features of antigen-presenting and immunosuppressive cells, suggesting that the CX3CR1+ population is uniquely suited to modulate the response of the adaptive immune arm. In this proposal, we will examine the origin of CX3CR1+ neutrophils, the myeloid progenitors that produce them and the cytokines that control their production, whether these progenitors are different from those that produce canonical CX3CR1NEG neutrophils, and the preferred anatomical sites where these cells are produced (Aim 1). We will assess their capacity to capture antigen in vivo and to activate T cells through antigen presentation, or to suppress the cytotoxic activity of CD8 T cells, in the context of lung cancer and vaccinia infection. We will examine the specific contribution of GM-CSF and IFNβ, two cytokines that regulate homeostasis and inflammation, for the functional reprogramming and production of these immune-modulatory neutrophils (Aim 2). By defining a specialized maturation path that produces functionally distinct neutrophils, we will evaluate the potential of the granulocytic compartment for therapeutic manipulation. Project Number: 1R01AI190922-01A1 | Fiscal Year: 2026 | NIH Institute/Center: National Institute of Allergy and Infectious Diseases (NIAID) | Principal Investigator: Andres Hidalgo | Institution: YALE UNIVERSITY, NEW HAVEN, CT | Award Amount: $735,631 | Activity Code: R01 | Study Section: Special Emphasis Panel[ZRG1 IIDA-A (81)] View on NIH RePORTER: https://reporter.nih.gov/project-details/1R01AI19092201A1