Perforin 2 controls unconventional cytokine release from mucosal APC project summary how professional antigen presenting cell (APC) populations focally deliver cytokines to t cells for shaping the…

Perforin 2 controls unconventional cytokine release from mucosal APC project summary how professional antigen presenting cell (APC) populations focally deliver cytokines to t cells for shaping the pro-inflammatory VS. Anti-inflammatory status of mucosal tissue remains incompletely understood. In particular, cytokines that lack n-terminal peptide sequence such as the IL-1 family cytokine IL-33 can't access conventional protein secretion pathways, which has led to the prevailing view that cell death is responsible for IL-33 release. This project is built upon an exciting set of preliminary data demonstrating that mucosal conventional dendritic cell (CDC) subsets, in both humans and mice, express the transmembrane pore-forming protein perforin-2, which at least in mice, facilitates IL-33 secretion. While in human CDC, we find perforin-2 expression primarily in an interferon regulatory factor 4 (IRF4) subset indicating the CDC2 lineage, in mouse CDC, we find perforin-2 in the CD103+ CDC1 subset known to express the transcription factors IRF8 and BATF3. Irrespective of this lineage distinction, both human and mouse CD11C+ cells in the respiratory mucosa contain cytoplasmic IL-33 protein. Our data demonstrate that inhibition of perforin-2 activity prevents IL-33 release from CDC and inhibits the proliferative expansion of a poorly understood ST2+GATA3+FOXP3+treg subset. Given that perforin-2 has been shown to also regulate type 1 IFN signaling through controlling ifnar responsiveness, we propose an important regulatory mechanism exists in humans and mice that is dependent upon mucosal APC that express perforin-2. This project tests the central hypothesis that APC require perforin-2 as an inducible plasma membrane conduit for unconventional cytokine delivery at the mucosal interface. Three specific aims (SA) will be investigated. SA1 will determine whether perforin-2+ APC predict treg subset abundance in sinonasal mucosa and define the transcriptional landscape of perforin-2+ APC. SA2 will define the perforin-2 domains required for IL-33 release, the diversity of perforin-2-dependent secreted molecules, and the requisite intracellular trafficking machinery responsible for perforin-2 plasma membrane localization during APC-t cell interactions. SA3 will directly test whether CDC1 and/or CDC2 subsets preferentially use perforin-2 for driving pathogen-specific t cell responses in mouse models of respiratory virus or helminth infection. Taken together, this mist project stands to uncover a new paradigm for understanding how CDC instruct immunity within the respiratory mucosa.