Programmed death-1 (PD-1) and its ligand PD-L1 are checkpoint molecules which regulate immune responses. Little is known about their functions in T cell migration and there are contradictory data about their roles in regulatory T cell (Treg) function. Here we show activated Tregs and CD4 effector T cells (Teffs) use PD-1/PD-L1 and CD80/PD-L1, respectively, to regulate transendothelial migration across lymphatic endothelial cells (LECs). Antibody blockade of Treg PD-1, Teff CD80 (the alternative ligand for PD-L1), or LEC PD-L1 impairs Treg or Teff migration in vitro and in vivo. PD-1/PD-L1 signals through PI3K/Akt and ERK to regulate zipper junctional VE-cadherin, and through NFκB-p65 to up-regulate VCAM-1 expression on LECs. CD80/PD-L1 signaling up-regulates VCAM-1 through ERK and NFκB-p65. PD-1 and CD80 blockade reduces tumor egress of PD-1high fragile Tregs and Teffs into draining lymph nodes, respectively, and promotes tumor regression. These data provide roles for PD-L1 in cell migration and immune regulation.
Bibliographical noteFunding Information:
This work was supported by NIH grants R37AI062765, R01 AI114496, and P01 AI153003 to J.S.B.; RO1 HL155114 and R37AI34495 to B.R.B.; R01 HL11879 and P01 CA 065493 to B.R.B. and K.L.H. We thank Dr. Xiaoxuan Fan, Bryan Han, and Karen Underwood from UMB-Flow Core Facility for excellent help for flow cell sorting.
© 2022, The Author(s).