ZFYVE21 is a Mediator of Non-Canonical Hedgehog Signaling Activating NLRP3 Inflammasomes in a Pathologic Subset of CD4+PD-1hi T Cells

Abstract

Purpose ZFYVE21 is a Rab5 effector whose role(s) in cellular immunity are unknown. Here, we examined the role of ZFYVE21 as a mediator of Hedgehog signaling, specifically testing the hypothesis that Hedgehog-derived signals intended for proliferative wound repair may pathologically expand CD4+ T cells. Methods We peformed in vitro cultures using primary human endothelial cells, T cells, and B cells. We used a humanized mouse model involving surgical implantation of human artery xenografts in SCID/beige engrafted with human lymphoid cells. We validated salient findings using patient-derived biospecimens from patients with delayed graft function, a complement-mediated condition causing dysregulated tissue injury. Results Following complement-mediated injury, endothelial cells release Hh ligands to generate a highly activated population of memory CD4+ T cells (Tmem) abundantly expressing PD-1 and chemokine receptors for homing to peripheral but not lymphoid tissues. In this subset, non-canonical Hedgehog signaling upregulates ZFYVE21 to induce Akt2-dependent NLRP3 inflammasomes, a process eliciting IL-18-mediated cellular expansion. Hh-induced PD-1hi Tmem, NLRP3 inflammasomes, and lymphoid-specific ZFYVE21 regulate vascular injury in vivo. Patients with ischemia reperfusion injury show increased ZFYVE21 expression in Ki-67+PD-1hiCCR2+ Tmem, and patient-derived Hh ligands induce ZFYVE21. Conclusion ZFYVE21 links dysregulated non-canonical Hh signaling with T cell intrinsic NLRP3 inflammasome activity to expand a tissue homing subset of CD4+ T cells propagating peripheral injury.