4-1BB Signaling Synergizes with Programmed Death Ligand 1 Blockade To Augment CD8 T Cell Responses during Chronic Viral Infection

Abstract

Previous studies have identified the inhibitory role that the programmed death 1 (PD-1) pathway plays during chronic infection. Blockade of this pathway results in rescue of viral-specific CD8 T cells, as well as reduction of viral loads in mice chronically infected with lymphocytic choriomeningitis virus (LCMV). We tested the effect of combining PD ligand 1 (PD-L1) blockade with an agonistic regimen that induces 4-1BB costimulation during chronic LCMV infection. There is a boosting effect in the rescue of LCMV-specific CD8 T cell responses after dual treatment with PD-L1 blockade and 4-1BB agonistic Abs when the amount and timing of 4-1BB costimulation are carefully controlled. When PD-L1–blocking Abs are given together with a single low dose of anti–4-1BB agonistic Abs, there is an enhanced and stable expansion of viral-specific CD8 T cells. Conversely, when blocking Abs to PD-L1 are given with a repetitive high dose of anti–4-1BB, there is an initial synergistic expansion of viral-specific CD8 T cells by day 7, followed by dramatic apoptosis by day 14. Viral control paralleled CD8 T cell kinetics after dual treatment. By day 7 posttreatment, viral titers were lower in both of the combined regimens (compared with PD-L1 blockade alone). However, whereas the high dose of anti–4-1BB plus PD-L1 blockade resulted in rebound of viral titers to original levels, the low dose of anti–4-1BB plus PD-L1 blockade resulted in a stable reduction of viral loads. These findings demonstrate the importance of carefully manipulating the balance between activating and inhibitory signals to enhance T cell responses during chronic infection.

Anti-GITR Agonist Therapy Intrinsically Enhances CD8 T Cell Responses to Chronic Lymphocytic Choriomeningitis Virus (LCMV), Thereby Circumventing LCMV-Induced Downregulation of Costimulatory GITR Ligand on APC

“…5F, 5G and data not shown). The total number of IFN-g/CD107a coproducers following ex vivo GP [33][34][35][36][37][38][39][40][41] peptide restimulation was consistently, but not significantly higher, in DTA-1-treated animals (Fig. 5F).…”

“…Splenocytes were stained with tetramer and surface stain Abs for 1 h at 4˚C, after which cells were washed thoroughly and fixed in 4% paraformaldehyde for 30 min at 4˚C. For intracellular cytokine staining, splenocytes were cultured in complete medium with brefeldin A and monensin (BD Biosciences; catalog 554715) with 1 mg/ml H-2D b -restricted LCMV NP 396-404 , GP [33][34][35][36][37][38][39][40][41] , or GP 276-286 (Anaspec, Fremont, CA) and 0.5 mg/ml anti-CD107a or IgG1 isotype control (BD Biosciences) for 5 h, or 4 mg/ml I-A b -restricted LCMV GP 61-80 with 20 U/ml murine rIL-2 (eBioscience) for 5 h. Cells were then surface stained, fixed, permeabilized (BD Biosciences), and stained for intracellular cytokine production.…”

“…Freshly isolated splenocytes were incubated with or without 1 mM LCMV GP [33][34][35][36][37][38][39][40][41] peptide (Anaspec) for 1 h in complete medium at 37˚C. Cells were then washed thoroughly and labeled with 1 mM (unpulsed targets) or 10 mM (GP 33-41 pulsed targets) CFSE for 10 min at 37˚C in 0.1% BSA in PBS solution.…”

Transgenic 4-1BBL-engineered vaccine stimulates potent Gag-specific therapeutic and long-term immunity via increased priming of CD44+CD62Lhigh IL-7R+ CTLs with up- and downregulation of anti- and pro-apoptosis genes

“…[15][16][17][18][19] 4-1BBL synergizes with CD80 and PD-1 blockade to re-activate anergic T cells 20 and to augment CTL responses during chronic viral infection. 21 In addition, 4-1BBL signaling is also a critical component in the costimulation-dependent rescue of exhausted HIV-specific CTLs, 22 and the combination of 4-1BBL and CD40L signaling enhances the stimulation of HIV-1-specific CTLs. 23 Therefore, 4-1BBL becomes an attractive candidate signaling molecule to improve the efficacy of immunotherapy.…”

Costimulatory molecules as vaccine adjuvants: to 4-1BB or not to 4-1BB?

“…There are encouraging data available showing that low-dose agonistic 4-1BB antibody synergizes with programmed death-L1 blockade to rejuvenate exhausted antigen-specific CD8 T cells in a mouse model of chronic viral infection. 6 However, a repeat high dose of 4-1BB caused a transient increase followed by rapid decline in antigenspecific CD8 T cells. As with other immune activating agents, dose and timing of 4-1BB are critical to achieve the desired immune potentiating effects.…”