Functional plasticity shapes the neutrophil response to infection by Leishmania major in susceptible and resistant strains of mice

by Thiago DeSouza-Vieira, Marco Antônio M. Pretti, Phillipe Souza Lima Gomes, Heitor A. Paula-Neto, Amy Goundry, Michelle T. Nascimento, Sundar Ganesan, Triciana Gonçalves da Silva, Olena Kamenyeva, Juraj Kabat, Javier Manzella-Lapeira, Fábio B. Canto, Vanderlei da Silva Fraga-Junior, Mateus Eustáquio Lopes, Leonardo Gomes Vaz, Gabriela Pessenda, Andrea Paun, Anita L. Freitas-Mesquita, José Roberto Meyer-Fernandes, Mariana Boroni, Maria Bellio, Gustavo Batista Menezes, Joseph Brzostowski, Jeremy Mottram, David Sacks, Ana Paula C. A. Lima, Elvira Saraiva

Neutrophils rapidly infiltrate sites of infection and possess several microbicidal strategies, such as neutrophil extracellular traps release and phagocytosis. Enhanced neutrophil infiltration is associated with higher susceptibility to Leishmania infection, but neutrophil effector response contribution to this phenotype is uncertain. Here, we show that neutrophils from susceptible BALB/c mice (B/c) produce more NETs in response to Leishmania major than those from resistant C57BL/6 mice (B6), which are more phagocytic. The absence of neutrophil elastase contributes to phagocytosis regulation. Microarray analysis shows enrichment of genes involved in NET formation (mpo, pi3kcg, il1b) in B/c, while B6 shows upregulation of genes involved in phagocytosis and cell death (Arhgap12, casp9, mlkl, FasL). scRNA-seq in L. major-infected B6 showed heterogeneity in the pool of intralesional neutrophils, and we identified the N1 subset as the putative subpopulation involved with phagocytosis. In vivo, imaging validates NET formation in infected B/c ears where NETing neutrophils were mainly uninfected cells. NET digestion in vivo augmented parasite lymphatic drainage. Hence, a balance between NET formation and phagocytosis in neutrophils may contribute to the divergent phenotype observed in these mice.