Unleashing CD8+ T Cells for TB Defense

Univ Of Massachusetts Med Sch Worcester, Worcester MA

Investigators

Abstract

PROJECT SUMMARY This R21 application is based on exciting and novel preliminary data supporting the hypothesis that the orphan nuclear receptor NR4A1 restrains the protective function of CD8+ T cells in tuberculosis (TB). We found the NR4A1-/- mice control pulmonary infection with Mycobacterium tuberculosis (Mtb) significantly better than wildtype (WT) mice. A similar effect was observed in WT mice treated with the NR4A1 antagonist DIM-C. In an adoptive transfer experiment, NR4A1-/- CD8+ T cells protected Rag1-/- mice from aerosol Mtb infection better than transferred CD8+ T cells from NR4A1-/- or WT donors. This is remarkable since prior studies found little or no protection from transferred WT CD8+ T cells, which was confirmed in our experiment. Immunohistochemistry of lung TB lesions showed greater infiltration of CD8+ T cells in NR4A1-/- mice compared to WT. Analysis of bulk RNA sequencing data from purified lung CD8+ T cells from Mtb-infected mice identified upregulation of genes linked to cellular infiltrative capacity and cytotoxicity in NR4A1-/- compared to WT hosts. If true, these findings will advance the field of cellular immunity in TB and offer translation potential for NR4A1 inhibition as host-directed therapy. Expression of NR4A1 is induced by T cell receptor signaling, which is the predominant mechanism for regulating its activity. We found that NR4A1 mRNA is increased in the lungs of Mtb-infected mice, raising the fundamental question whether NR4A1-regulated T cell tolerance supports a pathogen-permissive environment in TB. The goal of this R21 application is to confirm and extend key findings of the TB phenotyping, adoptive transfer, and DIM-C treatment experiments, and to enhance these studies with more detailed outcome measures. We also plan to perform single cell RNA sequencing of lung leukocytes and spatial transcriptomic studies in Mtb-infected NR4A1-/- and WT mice as a first step towards identifying and prioritizing mechanistic hypotheses on which to base a future RO1 proposal. Accordingly, we describe a research plan that is feasible to complete within two years with the deliverables of an initial publication and a competitive RO1 application.