LAG-3 sustains TOX expression and regulates the CD94/NKG2-Qa-1b axis to govern exhausted CD8 T cell NK receptor expression and cytotoxicity.

Exhausted CD8 T (T _ex ) cells in chronic viral infection and cancer have sustained co-expression of inhibitory receptors (IRs). T _ex cells can be reinvigorated by blocking IRs, such as PD-1, but synergistic reinvigoration and enhanced disease control can be achieved by co-targeting multiple IRs including PD-1 and LAG-3. To dissect the molecular changes intrinsic when these IR pathways are disrupted, we investigated the impact of loss of PD-1 and/or LAG-3 on T _ex cells during chronic infection. These analyses revealed distinct roles of PD-1 and LAG-3 in regulating T _ex cell proliferation and effector functions, respectively. Moreover, these studies identified an essential role for LAG-3 in sustaining TOX and T _ex cell durability as well as a LAG-3-dependent circuit that generated a CD94/NKG2 ⁺ subset of T _ex cells with enhanced cytotoxicity mediated by recognition of the stress ligand Qa-1b, with similar observations in humans. These analyses disentangle the non-redundant mechanisms of PD-1 and LAG-3 and their synergy in regulating T _ex cells.
Competing Interests: Declaration of interests E.J.W. is a member of the Parker Institute for Cancer Immunotherapy which supported this study. E.J.W. is an advisor for Arsenal Bioscience, Coherus, Danger Bio, Janssen, New Limit, Marengo, Pluto Immunotherapeutics, Prox Biosciences, Related Sciences, Santa Ana Bio, and Synthekine. E.J.W. is a founder of and holds stock in Arsenal Biosciences. A.H.S. has patents/pending royalties on the PD-1 pathway from Roche and Novartis and has research funding from IOME, AbbVie, and Taiwan Bio. A.H.S. serves as an advisor for Selecta, Elpiscience, Monopteros, Bicara, Fibrogen, IOME, Bioentre, Corner Therapeutics, Alixia, GlaxoSmithKline, Amgen, and Janssen. D.A.A.V. has patents covering LAG-3, with others pending. D.A.A.V. is a co-founder and stockholder for Novasenta, Tizona, and Trishula; a stockholder for Oncorus and Werewolf; and has patents licensed to Bristol Myers Squibb (BMS) and Novasenta. D.A.A.V. is a scientific advisor for Tizona, Werewolf, F-Star, Bicara, Apeximmune, and T7/Imreg Bio and is a consultant for BMS, Incyte, Regeneron, Ono Pharma, Peptone, and Avidity Partners. D.A.A.V. receives research funding from BMS and Novasenta. O.K. holds stock in Arsenal Biosciences and is an employee of Orange Grove Bio. A.C.H. consults for Immunai and received research funding from BMS and Merck. J.R.G. consults for Arsenal Biosciences.
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