Expression of a core gene module of anergy governs maternal CD8+ T cell hypofunction after pregnancy

Abstract Maternal exposure to fetal antigen during pregnancy results in T cell alloimmunization that impacts immunologic responses later in postpartum life. To study the mechanisms of memory T cell differentiation during pregnancy, we transferred 1x106 CD45.2 OVA-specific OT-1 CD8 T cells into CD45.1 mice. Mice were either 1) mated with Act-mOVA males (pOVA), 2) received an OVA skin graft from an Act-mOVA donor (gOVA) or 3) had no antigen exposure (naïve). Sixty days after cell transfer (~30 days after delivery in pOVA mice and ~30 days after skin graft rejection in gOVA mice), OT-1 cells were recovered for functional, phenotypic, and transcriptional analysis. Whereas gOVA OT-1 T cells differentiated into PD-1intCD127+CD62L+ central memory cells with enhanced recall capacity, pOVA OT-1 T cells persisted as hypofunctional PD-1hi long-lived effectors (CD127-CD62L-). pOVA OT-1 cells were hypoproliferative during recall challenge [Fold expansion over naïve: 4.6 (gOVA) vs. 1.5 (pOVA); p<0.001] and demonstrated impaired cytotoxicity and cytokine production [%IFNγ+TNFα+ = 46±6% (gOVA), vs. 7±6% (pOVA); p<0.001]. Transcriptional profiling using RNA-seq revealed 400 differentially expressed genes (FDR<0.05) between gOVA and pOVA OT-1 T cells; these included anergy-inducing genes such as master regulators of T cell hypofunction (i.e. Tox), repressors of the IL-2 locus (i.e. Aiolos), modulators of calcium responses (i.e. CD38), and enzymes which mediate ubiquitination of signaling molecules of the MAP kinase pathway (i.e. Deltex1). Altogether, pregnancy alloimmunization primes a program of hypofunction in long-lived maternal CD8+ T cell that is shared with other models of anergy.