High Resolution Spatial Transcriptomics using seq-FISH+

Much has been learned about mechanisms that drive autoimmunity by studying vitiligo, a dis- ease of the skin that results from destruction of pigment-producing melanocytes. This results in disfiguring white spots that are particularly devastating for those with darker skin, which thus leads to health disparities for the most vulnerable of our population. We generated an extensive set of preliminary data using single cell RNA sequencing (scRNA-Seq) that revealed hun- dreds of conversations that are unique to vitiligo lesions involving every cell type of the epider- mis. These data indicate that cells and their signaling networks within affected and unaffected vitiligo skin are in fact more complex than previously appreciated. Yet because scRNA-Seq re- quires disruption of the tissue, the position of each cell and their communications within the skin remains unknown. We hypothesize that cells connected in silico by matching induced ligand-receptor expression are in close physical proximity in situ, and that T cell clones marked by identical T cell receptor (TCR) sequences associate in physical contact with melanocytes. The objective of the High- Resolution Spatial Transcriptomics Research Core using sequential fluorescence in situ hybridi- zation (seqFISH+) is to use our highly innovative platform to provide spatial context to T cell clonality, cellular positioning, and cell-cell communications revealed by the complementary, syn- ergistic Center Projects 1+2. Our seqFISH+ platform provides a cutting-edge, innovative ap- proach to map RNA expression in tissues with high accuracy and sub-diffraction-limit resolution, allowing for identification of cell classes, expressed genes, and spatial organization in tissues. This approach will be applied in the following specific aims: 1) Identify the position and distribu- tion of T cell clones marked by unique TCR sequences within tissue; and 2) Reveal the spatial organization of communicating cells by receptor-ligand mapping directly within vitiligo lesions. We will use punch biopsies taken from the same vitiligo lesions that have been analyzed by sin- gle cell techniques in each Project. We will design seqFISH+ probes that complement TCR se- quences and ligand-receptor pairs for hybridization, which will indicate the spatial distribution of T cell clonality and cell-cell communications through ligand-receptor pairing. This Research core combines a highly innovative conceptual approach with cutting-edge technology. The prelimi- nary data, investigative team, and innovative plan provides a robust and unique opportunity for discovery of the fundamental mechanisms by which immune cells target self-tissues, which may lead to improved treatment strategies.