"Single-cell Secretion Analysis Reveals Paracrine Strategies for Coordinating Innate Immune Responses in Cell Populations"

Kathryn Miller-Jensen, PhD
Assistant Professor, Department of Biomedical Engineering
Yale University
 
Seminar will be made available via videoconference in the Health Sciences Research Building, room E182 and Technology Enterprise Park, room 104.

Cell responses are mediated by intermediate signals that are secreted and sensed by the same cells and are subject to significant cell-to-cell heterogeneity. The propagation of these intermediate signals by extracellular signaling impacts the collective cell-population response, but the contribution of autocrine versus paracrine signaling is difficult to analyze. To address this, we have combined multiplexed, microwell single-cell secretion measurements with cell-population data to uncover the role of paracrine signaling in shaping the inflammatory response in human macrophages following toll-like receptor 4 (TLR4) stimulation with lipopolysaccharide (LPS). We demonstrate that loss of paracrine signaling upon single-cell isolation in microwells significantly alters secretion of some LPS-stimulated cytokines. Gaussian graphical models of these single-cell “perturbation” data sets specifically uncover regulatory connections between cytokines in the LPS-stimulated network. Tumor necrosis factor-α (TNF), the most highly connected cytokine in the network, exhibits highly heterogeneous secretion, such that a small fraction of cells appears to drive total TNF output in the cell population. Using a mechanistic ODE model fit to our single-cell data, we demonstrate that this small fraction of high TNF secretors combined with positive feedback amplifies the pro-inflammatory IL-6 response in cell populations. Overall, our results reveal a novel role for paracrine cell-to-cell communication in coordinating a rapid and reliable innate immune response in spite of underlying cell-to-cell heterogeneity. 

Melissa Kemp, PhD - faculty host