Immunology Team Contributions to the LSB

National Institute Of Allergy And Infectious Diseases

Investigators

Linked publications & trials

Abstract

Over the past several years, we have contributed to this project in several ways. First, we continue to contribute to a detailed analysis of multi-ligand stimulation of macrophages by TLR ligands that is leading to the refinement of a detailed biochemical model of these processes using the Simmune modeling environment, research that is now being extended by former LBS fellow Dr. Rachel Gottschalk in collaboration with LISB PIs Dr. Martin Meier-Schellersheim and Dr. Aleksandra Nita-Lazar. We previously developed a model system for employing the tools of systems biology to investigate the unexplored roles of many NLRs and observed profound effects of very small changes in intracellular protein concentration on signaling through the NOD1 pathway. These findings have led us to focus attention on how small small (1-2 fold changes in gene expression, as seen with many eQTLs), can lead to disease by imbalancing activation and negative regulatory pathways. We suspect this type of dysregulation might contribute to various autoimmune states. Previous work has shown that monoclonal T cells with variation in CD8 coreceptor expression show marked differences in the EC50 needed for pMHC ligand stimulation of TCR signaling pathways such as ERK. This microstate related to CD8 expression varies over time, with dim cells becoming bright for CD8 and more sensitive to antigen and bright cells becoming dim and less sensitive to antigen within a 240-48 hour timeframe, in the absence of cell division. These data indicate that even the current methods for single cell analysis that cluster all cells of a related phenotype together (e.g., in a UMAP for scRNAseq) will miss events linked to cells in the extreme of this varying expression distribution who experience an environment able to elicit responses due to the hypersensitive state of a few cells in the ‘tail of the curve’. These time fluctuations in cell state have important implications for better understanding when individual immune cells respond to perturbations, when they might exceed regulatory control thresholds, and how small eQTL-level differences in average gene expression might contribute to disease propensity. This argues that we need new methods for examination of individual cell responses in complex tissue environments, and we have approached this issue with the development of assays such as for nuclear NFAT as a direct readout of contemporaneous TCR signaling in tissue sections subjected to multiplex immunofluorescent staining (see AI000545-37 and AI000758-28). Lastly, using data from a cohort of immunized human volunteers and new bioinformatics methods, we have uncovered changes in innate immune populations that correlate with responses to the adjuvant in an experimental bird flu (H5N1) vaccine. These findings will help mesh our analysis of mouse data involving the same adjuvant material where we could perform much denser time course studies in muscle and lymphoid tissue (AI000758-28) with human results.