SRA

Neutrophils are innate immune cells involved in the elimination of pathogens. Recent studies showed that neutrophils can also act as antigen presenting cells (APC) to induce adaptive immune responses. Specific neutrophil populations (Na and Nb) with different levels of APC markers and in vitro distinct capacity to generate vaccinia virus (VACV)-specific CD8 T cell responses have been shown. However, how these neutrophil subtypes exert their role in vivo and how manipulation of Nb/Na ratio can influence vaccine-mediated immune responses are not known. In the context of VACV infection, we characterized HIV-specific CD8 T cell responses, delineated neutrophil transcriptomic profiles and described neutrophil dynamic behaviors in the spleen. By splenic multiphoton intravital microscopy (MV-IVM), we could distinguish both neutrophil subtypes and found that they showed distinct migratory and motility patterns and different ability to interact with CD8 T cells and move towards them. After analysis of adhesion, inflammatory and migration receptors from peritoneal cavity, blood and spleen, we defined that Nb neutrophils overexpressed the trans-endothelial migration marker a4b1integrin compared to Na subtype. Finally, by inhibiting a4b1integrin, we increased the Nb/Na ratio in peritoneal cavity and spleen, and in turn enhanced CD8 T cell responses to HIV-antigens. These findings provide significant advancements in the comprehension of neutrophil-based control of adaptive immune system. These results are relevant in vaccine vector design that could induce distinct neutrophil subtypes and, in consequence modulate antigen-specific T cell responses. Overall design: Bulk RNA-seq of Na and Nß shorted from pertinoneal washes of three mice immunized with 10^7 pfu of NYVAC-C ?3