The immune system has the powerful ability to swiftly mobilize in response to challenge, migrating between and within tissues to locally deliver inflammatory mediators that can be anti-microbial, anti-tumor or auto destructive. Most infected/inflamed tissues express elevated levels of many chemokines and most chemokine receptors (CRs) can bind to multiple ligands, creating a highly redundant network of signals. The optimization of immune cell navigation through such a complex microenvironment remains unclear. Indeed, current immunotherapies for various cancers have exposed deficiencies in our understanding of how effector T cells (Te) access and position themselves in inflamed tissues, with very inefficient recruitment/retention of CAR T cells into the tumor itself. Such microanatomical positioning driven by CRs and chemoattractants exposes Te to regional antigen and inflammatory signals that likely tune transcriptional programs to boost or restrain effector functions. Indeed, single cell transcriptomics analyses in infected and malignant tissues point to significant functional heterogeneity in tissue Te cells, but lack spatial and temporal information that shape such heterogeneity. We have used an optogenetic strategy to “timestamp” Th1 cells within inflamed tissues and have found an unexpected change in CR expression based on time from tissue entry. This proposal aims to gain new knowledge of the temporal use of CRs that impact Th1 functional (re)programing. Such insight would enable design of targeted therapeutic approaches that harness or manipulate Te within the target tissues of infection, inflammation or malignancy. We have utilized in vivo optogenetic approaches combined with RNAseq to follow changes in CR expression by Te in the inflamed skin. Our data reveal a striking temporal regulation of CR transcription by Th1 cells following tissue entry. Disruption of this sequence of CR expression comprises Th1 function. We hypothesize that CR gene expression modulated in a temporal fashion enables incoming effector T cells to differentially sense chemotactic cues for correct tissue positioning. Moreover, location-specific events of tissue entry, early activation, through to positioning at the infection foci transmit distinct signals that hone the Th1 transcriptional program to optimize effector function. Tested in the following aims:
Specific Aim 1. Signals that dynamically regulate CR expression and Th1 intra-tissue programing.
Specific Aim 2. Stage-specific CR requirements.
Specific Aim 3. Biological impact of temporal regulation of CR expression.